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251 (number)

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Title: 251 (number)  
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Subject: List of prime numbers, 250 (number), 252 (number), Sophie Germain prime, 500 (number)
Collection: Integers
Publisher: World Heritage Encyclopedia

251 (number)

250 251 252
Cardinal two hundred fifty-one
Ordinal 251st
(two hundred and fifty-first)
Factorization 251
Prime 54th
Roman numeral CCLI
Binary 111110112
Ternary 1000223
Quaternary 33234
Quinary 20015
Senary 10556
Octal 3738
Duodecimal 18B12
Hexadecimal FB16
Vigesimal CB20
Base 36 6Z36

251 (two hundred [and] fifty-one) is the natural number between 250 and 252. It is also a prime number.

In mathematics

251 is a Sophie Germain prime.[1] Every 5 × 5 matrix has exactly 251 square submatrices.[2] 251 is a de Polignac number, meaning that it is odd and cannot be formed by adding a power of two to a prime number.[3][4] It is the smallest number that can be formed in more than one way by summing three positive cubes:[5][6]

251 = 2^3 + 3^3 + 6^3 = 1^3 + 5^3 + 5^3.


  1. ^ "Sloane's A005384 : Sophie Germain primes p: 2p+1 is also prime", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ "Sloane's A030662 : Number of combinations of n things from 1 to n at a time, with repeats allowed", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ^ "Sloane's A006285 : Odd numbers not of form p + 2^x (de Polignac numbers)", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  4. ^ Kozek, Mark Robert (2007), Applications of Covering Systems of Integers and Goldbach's Conjecture for Monic Polynomials, PhD dissertation, University of South Carolina, p. 14,  .
  5. ^ "Sloane's A008917 : Numbers that are the sum of 3 positive cubes in more than one way", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  6. ^ De Koninck, Jean-Marie (2009), Those fascinating numbers, Providence, RI: American Mathematical Society, p. 64,  .
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