2000 (number) - AbsoluteAstronomy.com


Cardinal Cardinal number In mathematics, cardinal numbers, or cardinals for short, are a generalization of the natural numbers used to measure the cardinality of sets. The cardinality of a finite set is a natural number – the number of elements in the set. The transfinite cardinal numbers describe the sizes of infinite...	2000 two thousand
Ordinal Ordinal number In set theory, an ordinal number, or just ordinal, is the order type of a well-ordered set. They are usually identified with hereditarily transitive sets. Ordinals are an extension of the natural numbers different from integers and from cardinals...	2000th two thousandth
Factorization Factorization In mathematics, factorization or factoring is the decomposition of an object into a product of other objects, or factors, which when multiplied together give the original...
Roman numeral	MM
Roman numeral (Unicode)	MM, mm
Binary Binary numeral system The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...	11111010000
Octal Octal The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7. Numerals can be made from binary numerals by grouping consecutive binary digits into groups of three...	3720
Duodecimal Duodecimal The duodecimal system is a positional notation numeral system using twelve as its base. In this system, the number ten may be written as 'A', 'T' or 'X', and the number eleven as 'B' or 'E'...	11A8
Hexadecimal Hexadecimal In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...	7D0

2000 (two thousand) is the natural number

Natural number

In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...

following 1999 and preceding 2001.

Two thousand is the highest number expressible using only two unmodified characters in roman numerals

Roman numerals

The numeral system of ancient Rome, or Roman numerals, uses combinations of letters from the Latin alphabet to signify values. The numbers 1 to 10 can be expressed in Roman numerals as:...

(MM).

Two thousand is also:

In the name of the products Lever 2000 and Grecian 2000, Windows 2000
Windows 2000
Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the...
In Star Trek
Star Trek
Star Trek is an American science fiction entertainment franchise created by Gene Roddenberry. The core of Star Trek is its six television series: The Original Series, The Animated Series, The Next Generation, Deep Space Nine, Voyager, and Enterprise...

, the registry number of the USS Excelsior, NX-2000 in Star Trek III: The Search for Spock, and NCC-2000 commanded by Hikaru Sulu
Hikaru Sulu
Hikaru Sulu is a character in the Star Trek media franchise. First portrayed by George Takei in the original Star Trek series, Sulu also appears in the animated Star Trek series, the first six Star Trek movies, one episode of Star Trek: Voyager, and in numerous books, comics, and video games...

in Star Trek VI: The Undiscovered Country.
The postal code for Antwerp (Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

) and Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

(Australia)

Selected numbers in the range 2001–2999

2001 – sphenic number
Sphenic number
In number theory, a sphenic number is a positive integer which is the product of three distinct prime numbers.Note that this definition is more stringent than simply requiring the integer to have exactly three prime factors; e.g. 60 = 22 × 3 × 5 has exactly 3 prime factors, but is not sphenic.All...
2003 – Sophie Germain prime
Sophie Germain prime
In number theory, a prime number p is a Sophie Germain prime if 2p + 1 is also prime. For example, 23 is a Sophie Germain prime because it is a prime and 2 × 23 + 1 = 47, and 47 is also a prime number...

and the smallest prime number in 2000's
2005 – A vertically symmetric number
2011 – Sexy prime
Sexy prime
In mathematics, a sexy prime is a prime number that differs from another prime number by six. For example, the numbers 5 and 11 are both sexy primes, because they differ by 6...

number. Also, sum of eleven consecutive primes: 2011=157+163+167+173+179+181+191+193+197+199+211.
2015 – Lucas–Carmichael number
2016 – triangular number
Triangular number
A triangular number or triangle number numbers the objects that can form an equilateral triangle, as in the diagram on the right. The nth triangle number is the number of dots in a triangle with n dots on a side; it is the sum of the n natural numbers from 1 to n...
2017 – Mertens function zero. (2011, 2017) is a sexy prime
Sexy prime
In mathematics, a sexy prime is a prime number that differs from another prime number by six. For example, the numbers 5 and 11 are both sexy primes, because they differ by 6...

pair.
2020 – sum of the totient function for the first 81 integers
2024 – tetrahedral number
Tetrahedral number
A tetrahedral number, or triangular pyramidal number, is a figurate number that represents a pyramid with a triangular base and three sides, called a tetrahedron...
2025 – , sum of the cubes of the first nine integers, centered octagonal number
Centered octagonal number
A centered octagonal number is a centered figurate number that represents an octagon with a dot in the center and all other dots surrounding the center dot in successive octagonal layers...
2027 – safe prime
Safe prime
A safe prime is a prime number of the form 2p + 1, where p is also a prime. The first few safe primes are...
2029 – member of the Mian–Chowla sequence
2030 – ,
2031 – centered pentagonal number
Centered pentagonal number
A centered pentagonal number is a centered figurate number that represents a pentagon with a dot in the center and all other dots surrounding the center in successive pentagonal layers...
2039 – Sophie Germain prime, safe prime
2047 – super-Poulet number, Woodall number
Woodall number
In number theory, a Woodall number is any natural number of the formfor some natural number n. The first few Woodall numbers are:Woodall numbers were first studied by Allan J. C. Cunningham and H. J. Woodall in 1917, inspired by James Cullen's earlier study of the similarly-defined Cullen numbers...

, decagonal number
Decagonal number
A decagonal number is a figurate number that represents a decagon. The n-th decagonal number is given by the formulaThe first few decagonal numbers are:...

. Also, 2047 = 2¹¹ − 1 = 23 × 89 and is the first Mersenne number that is composite for a prime exponent.
2048 – power of two
Power of two
In mathematics, a power of two means a number of the form 2n where n is an integer, i.e. the result of exponentiation with as base the number two and as exponent the integer n....
2056 – magic constant
Magic constant
The magic constant or magic sum of a magic square is the sum of numbers in any row, column, and diagonal of the magic square. For example, the magic square shown below has a magic constant of 15....

of n×n normal magic square
Magic square
In recreational mathematics, a magic square of order n is an arrangement of n2 numbers, usually distinct integers, in a square, such that the n numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square contains the integers from 1 to n2...

and n-queens problem
Eight queens puzzle
The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens attack each other. Thus, a solution requires that no two queens share the same row, column, or diagonal...

for n = 16.
2060 – sum of the totient function for the first 82 integers
2063 – Sophie Germain prime, safe prime
2069 – Sophie Germain prime
2070 – pronic number
Pronic number
A pronic number, oblong number, rectangular number or heteromecic number, is a number which is the product of two consecutive integers, that is, n . The n-th pronic number is twice the n-th triangular number and n more than the n-th square number...
2080 – triangular number
2093 – Mertens function zero
2095 – Mertens function zero
2096 – Mertens function zero
2097 – Mertens function zero
2099 – Mertens function zero, safe prime, highly cototient number
Highly cototient number
In number theory, a branch of mathematics, a highly cototient number is a positive integer k which is above one and has more solutions to the equation...
2100 – Mertens function zero
2101 – centered heptagonal number
Centered heptagonal number
A centered heptagonal number is a centered figurate number that represents a heptagon with a dot in the center and all other dots surrounding the center dot in successive heptagonal layers...
2107 – member of a Ruth–Aaron pair with 2108 (first definition)
2108 – member of a Ruth–Aaron pair with 2107 (first definition)
2109 – square pyramidal number
Square pyramidal number
In mathematics, a pyramid number, or square pyramidal number, is a figurate number that represents the number of stacked spheres in a pyramid with a square base...
2112 – The break-through album of the band Rush
2112 (album)
2112 is the fourth studio album by Canadian rock band Rush, released in 1976.The album features an eponymous seven-part suite written by Geddy Lee and Alex Lifeson, with lyrics written by Neil Peart telling a dystopian story set in the year 2112. The album is sometimes described as a concept album...
2113 – Mertens function zero, Proth prime, centered square number
Centered square number
In elementary number theory, a centered square number is a centered figurate number that gives the number of dots in a square with a dot in the center and all other dots surrounding the center dot in successive square layers. That is, each centered square number equals the number of dots within a...
2116 –
2117 – Mertens function zero
2119 – Mertens function zero
2120 – Mertens function zero
2122 – Mertens function zero
2125 – nonagonal number
2127 – sum of the first 34 primes
2129 – Sophie Germain prime
2135 – Mertens function zero
2136 – Mertens function zero
2138 – Mertens function zero
2141 – Sophie Germain prime
2142 – sum of the totient function for the first 83 integers
2145 – triangular number
2162 – pronic number
2166 – sum of the totient function for the first 84 integers
2169 – Leyland number
Leyland number
In number theory, a Leyland number is a number of the form xy + yx, where x and y are integers greater than 1. The first few Leyland numbers are...
2171 – Mertens function zero
2172 – Mertens function zero
2178 – reverses when multiplied by 4
2175 – smallest number requiring 143 seventh powers for Waring representation
2176 – pentagonal pyramidal number
Pentagonal pyramidal number
A pentagonal pyramidal number is a figurate number that represents the number of objects in a pyramid with a pentagonal base. The nth pentagonal pyramidal number is equal to the sum of the first n pentagonal numbers....

, centered pentagonal number
2179 – Wedderburn–Etherington number
2187 – , vampire number
Vampire number
In mathematics, a vampire number is a composite natural number v, with an even number of digits n, that can be factored into two integers x and y each with n/2 digits and not both with trailing zeroes, where v contains precisely all the digits from x and from y, in any order, counting multiplicity...

, perfect totient number
Perfect totient number
In number theory, a perfect totient number is an integer that is equal to the sum of its iterated totients. That is, we apply the totient function to a number n, apply it again to the resulting totient, and so on, until the number 1 is reached, and add together the resulting sequence of numbers;...
2188 – Motzkin number
Motzkin number
In mathematics, a Motzkin number for a given number n is the number of different ways of drawing non-intersecting chords on a circle between n points. The Motzkin numbers have very diverse applications in geometry, combinatorics and number theory...
2197 –
2199 – perfect totient number
2201 – only non-palindromic number whose cube
Cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube can also be called a regular hexahedron and is one of the five Platonic solids. It is a special kind of square prism, of rectangular parallelepiped and...

is palindromic, also no fourth or higher powers are palindromic for non-palindromic numbers
2205 – odd abundant number
2207 – safe prime, Lucas prime
2208 – Keith number
2209 – , centered octagonal number
2211 – triangular number
2222 – repdigit
Repdigit
In recreational mathematics, a repdigit is a natural number composed of repeated instances of the same digit, most often in the decimal numeral system....
2223 – Kaprekar number
Kaprekar number
In mathematics, a Kaprekar number for a given base is a non-negative integer, the representation of whose square in that base can be split into two parts that add up to the original number again. For instance, 45 is a Kaprekar number, because 45² = 2025 and 20+25 = 45. The Kaprekar numbers are...
2230 – sum of the totient function for the first 85 integers
2232 – decagonal number
2245 – centered square number
2254 – member of the Mian–Chowla sequence
2255 – octahedral number
Octahedral number
In number theory, an octahedral number is a figurate number that represents the number of spheres in an octahedron formed from close-packed spheres...
2256 – pronic number
2269 – cuban prime
2272 – sum of the totient function for the first 86 integers
2273 – Sophie Germain prime
2276 – sum of the first 35 primes, centered heptagonal number
2278 – triangular number
2287 – balanced prime
2294 – Mertens function zero
2295 – Mertens function zero
2296 – Mertens function zero
2299 – member of a Ruth–Aaron pair with 2300 (first definition)
2300 – tetrahedral number, member of a Ruth–Aaron pair with 2299 (first definition)
2301 – nonagonal number
2304 –
2306 – Mertens function zero
2309 – primorial prime
Primorial prime
In mathematics, primorial primes are prime numbers of the form pn# ± 1, where:The first few primorial primes are, the largest known primorial prime is 843301# - 1 with 365,851 digits, found in 2010 by the PrimeGrid project....

, Mertens function zero, highly cototient number
2310 – fifth primorial
Primorial
In mathematics, and more particularly in number theory, primorial is a function from natural numbers to natural numbers similar to the factorial function, but rather than multiplying successive positive integers, only successive prime numbers are multiplied...
2311 – primorial prime
2321 – Mertens function zero
2322 – Mertens function zero
2326 – centered pentagonal number
2328 – sum of the totient function for the first 87 integers, the number of groups of order 128, see http://www-public.tu-bs.de:8080/~beick/soft/small/small.html.
2331 – centered cube number
Centered cube number
A centered cube number is a centered figurate number that represents a cube. The centered cube number for n is given byn^3 + ^3.The first few centered cube numbers are...
2338 – Mertens function zero
2339 – Sophie Germain prime
2346 – triangular number
2351 – Sophie Germain prime
2352 – pronic number
2357 – Smarandache–Wellin prime
2368 – sum of the totient function for the first 88 integers
2378 – Pell number
Pell number
In mathematics, the Pell numbers are an infinite sequence of integers that have been known since ancient times, the denominators of the closest rational approximations to the square root of 2. This sequence of approximations begins 1/1, 3/2, 7/5, 17/12, and 41/29, so the sequence of Pell numbers...
2379 – member of the Mian–Chowla sequence
2381 – centered square number
2393 – Sophie Germain prime
2397 – sum of the squares of the first ten primes
2399 – Sophie Germain prime
2400 – perfect score on SAT
SAT
The SAT Reasoning Test is a standardized test for college admissions in the United States. The SAT is owned, published, and developed by the College Board, a nonprofit organization in the United States. It was formerly developed, published, and scored by the Educational Testing Service which still...

tests administered after 2005
2401 – , , centered octagonal number
2415 – triangular number
2417 – balanced prime
2425 – decagonal number
2427 – sum of the first 36 primes
2437 – cuban prime
2447 – safe prime
2450 – pronic number
2456 – sum of the totient function for the first 89 integers
2458 – centered heptagonal number
2459 – Sophie Germain prime, safe prime
2465 – magic constant
Magic constant
The magic constant or magic sum of a magic square is the sum of numbers in any row, column, and diagonal of the magic square. For example, the magic square shown below has a magic constant of 15....

of n×n normal magic square
Magic square
In recreational mathematics, a magic square of order n is an arrangement of n2 numbers, usually distinct integers, in a square, such that the n numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square contains the integers from 1 to n2...

and n-queens problem
Eight queens puzzle
The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens attack each other. Thus, a solution requires that no two queens share the same row, column, or diagonal...

for n = 17, Carmichael number
2470 – square pyramidal number
2480 – sum of the totient function for the first 90 integers
2481 – centered pentagonal number
2484 – nonagonal number
2485 – triangular number
2491 – member of Ruth–Aaron pair with 2492 under second definition
2492 – member of Ruth–Aaron pair with 2491 under second definition
2500 –
2501 – Mertens function zero
2502 – Mertens function zero
2510 – member of the Mian–Chowla sequence
2513 – member of the Padovan sequence
Padovan sequence
The Padovan sequence is the sequence of integers P defined by the initial valuesP=P=P=1,and the recurrence relationP=P+P.The first few values of P are...
2517 – Mertens function zero
2519 – the smallest number when divided by 10 gives a remainder 9; when divided by 9 gives a remainder 8; when divided by 7 gives a remainder 6; and so on until when divided by 2 gives a remainder 1
2520 – highly composite number
Highly composite number
A highly composite number is a positive integer with more divisors than any positive integer smaller than itself.The initial or smallest twenty-one highly composite numbers are listed in the table at right....

; smallest number divisible by numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 12 ; colossally abundant number
Colossally abundant number
In mathematics, a colossally abundant number is a natural number that, in some rigorous sense, has a lot of divisors...

; Harshad number
Harshad number
A Harshad number, or Niven number in a given number base, is an integer that is divisible by the sum of its digits when written in that base. Harshad numbers were defined by D. R. Kaprekar, a mathematician from India. The word "Harshad" comes from the Sanskrit + , meaning joy-giver. The Niven...

in several bases. It is also the highest number with more divitors than any number less than double itself.
2521 – centered square number
2522 – Mertens function zero
2523 – Mertens function zero
2524 – Mertens function zero
2525 – Mertens function zero
2530 – Mertens function zero, Leyland number
2533 – Mertens function zero
2537 – Mertens function zero
2538 – Mertens function zero
2543 – Sophie Germain prime
2549 – Sophie Germain prime
2550 – pronic number
2552 – sum of the totient function for the first 91 integers
2556 – triangular number
2567 – Mertens function zero
2568 – Mertens function zero. Also number of digits in the decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....

expansion of 1000!
Factorial
In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n...

, or the product
Product (mathematics)
In mathematics, a product is the result of multiplying, or an expression that identifies factors to be multiplied. The order in which real or complex numbers are multiplied has no bearing on the product; this is known as the commutative law of multiplication...

of all natural number
Natural number
In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...

s from 1 to 1000.
2570 – Mertens function zero
2579 – safe prime
2580 – Keith number
2584 – Fibonacci number
Fibonacci number
In mathematics, the Fibonacci numbers are the numbers in the following integer sequence:0,\;1,\;1,\;2,\;3,\;5,\;8,\;13,\;21,\;34,\;55,\;89,\;144,\; \ldots\; ....

, sum of the first 37 primes
2596 – sum of the totient function for the first 92 integers
2600 – tetrahedral number, member of a Ruth–Aaron pair with 2601 (first definition)
- 2600 Hz
  Hertz
  The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
  
  is the tone used by a blue box
  Blue box
  An early phreaking tool, the blue box is an electronic device that simulates a telephone operator's dialing console. It functioned by replicating the tones used to switch long-distance calls and using them to route the user's own call, bypassing the normal switching mechanism...
  
  to defeat toll charges on long distance telephone calls.
- 2600: The Hacker Quarterly
  2600: The Hacker Quarterly
  2600: The Hacker Quarterly is an American publication that specializes in publishing technical information on a variety of subjects including telephone switching systems, Internet protocols and services, as well as general news concerning the computer "underground" and left wing, and sometimes ,...
  
  is a magazine named after the above.
- The Atari 2600
  Atari 2600
  The Atari 2600 is a video game console released in October 1977 by Atari, Inc. It is credited with popularizing the use of microprocessor-based hardware and cartridges containing game code, instead of having non-microprocessor dedicated hardware with all games built in...
  
  was a popular video game console
  Video game console
  A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...
  
  .
- Current year (Zoroastrian calendar)
2601 – , member of a Ruth–Aaron pair with 2600 (first definition)
2620 – amicable number
Amicable number
Amicable numbers are two different numbers so related that the sum of the proper divisors of each is equal to the other number. A pair of amicable numbers constitutes an aliquot sequence of period 2...

with 2924
2626 – decagonal number
2628 – triangular number
2632 – number of consecutive baseball games played by Cal Ripken, Jr.
Cal Ripken, Jr.
Calvin Edwin "Cal" Ripken, Jr. , nicknamed "Iron Man", is a former Major League Baseball shortstop and third baseman. He played his entire 21-year baseball career for the Baltimore Orioles ....
2641 – centered pentagonal number
2647 – centered heptagonal number
2652 – pronic number
2656 – sum of the totient function for the first 93 integers
2665 – centered square number
2674 – nonagonal number
2677 – balanced prime
2680 – number of 11-queens problem
Eight queens puzzle
The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens attack each other. Thus, a solution requires that no two queens share the same row, column, or diagonal...

solutions
2689 – Mertens function zero, Proth prime
2693 – Sophie Germain prime
2699 – Sophie Germain prime
2701 – triangular number, super-Poulet number
2702 – sum of the totient function for the first 94 integers
2704 –
2728 – Kaprekar number
2729 – highly cototient number
2731 – Wagstaff prime
2736 – octahedral number
2741 – Sophie Germain prime
2744 –
2747 – sum of the first 38 primes
2753 – Sophie Germain prime, Proth prime
2756 – pronic number
2774 – sum of the totient function for the first 95 integers
2775 – triangular number
2780 – member of the Mian–Chowla sequence
2783 – member of a Ruth–Aaron pair with 2784 (first definition)
2784 – member of a Ruth–Aaron pair with 2783 (first definition)
2791 – cuban prime
2806 – centered pentagonal number, sum of the totient function for the first 96 integers
2809 – , centered octagonal number
2813 – centered square number
2819 – Sophie Germain prime, safe prime
2821 – Carmichael number
2835 – odd abundant number, decagonal number
2843 – centered heptagonal number
2850 – triangular number
2862 – pronic number
2870 – square pyramidal number
2871 – nonagonal number
2872 – tetranacci number
2879 – safe prime
2897 – Markov number
Markov number
A Markov number or Markoff number is a positive integer x, y or z that is part of a solution to the Markov Diophantine equationx^2 + y^2 + z^2 = 3xyz,\,studied by .The first few Markov numbers are...
2902 – sum of the totient function for the first 97 integers
2903 – Sophie Germain prime, safe prime, balanced prime
2914 – sum of the first 39 primes
2915 – Lucas–Carmichael number
2916 –
2924 – amicable number with 2620
2925 – magic constant
Magic constant
The magic constant or magic sum of a magic square is the sum of numbers in any row, column, and diagonal of the magic square. For example, the magic square shown below has a magic constant of 15....

of n×n normal magic square
Magic square
In recreational mathematics, a magic square of order n is an arrangement of n2 numbers, usually distinct integers, in a square, such that the n numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square contains the integers from 1 to n2...

and n-queens problem
Eight queens puzzle
The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens attack each other. Thus, a solution requires that no two queens share the same row, column, or diagonal...

for n = 18, tetrahedral number, member of the Mian-Chowla sequence
2926 – triangular number
2939 – Sophie Germain prime
2944 – sum of the totient function for the first 98 integers
2963 – Sophie Germain prime, safe prime, balanced prime
2965 – greater of second pair of Smith brothers
Smith number
A Smith number is a composite number for which, in a given base , the sum of its digits is equal to the sum of the digits in its prime factorization. For example, 378 = 2 × 3 × 3 × 3 × 7 is a Smith number since 3 + 7 + 8 =...

, centered square number
2969 – Sophie Germain prime
2970 – harmonic divisor number
Harmonic divisor number
In mathematics, a harmonic divisor number, or Ore number , is a positive integer whose divisors have a harmonic mean that is an integer. The first few harmonic divisor numbers are...

, pronic number
2976 – centered pentagonal number
2997 – chiliagonal number
2999 – safe prime

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