251 (number)
From HandWiki
Short description: Natural number
| ||||
|---|---|---|---|---|
| Cardinal | two hundred fifty-one | |||
| Ordinal | 251st (two hundred fifty-first) | |||
| Factorization | prime | |||
| Prime | 54th | |||
| Greek numeral | ΣΝΑ´ | |||
| 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]
- the sum of three consecutive primes (79 + 83 + 89) and seven consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47).
- a Chen prime.
- an Eisenstein prime with no imaginary part.
- a de Polignac number, meaning that it is odd and cannot be formed by adding a power of two to a prime number.[2][3]
- the smallest number that can be formed in more than one way by summing three positive cubes:[4][5][math]\displaystyle{ 251 = 2^3 + 3^3 + 6^3 = 1^3 + 5^3 + 5^3. }[/math]
Every 5 × 5 matrix has exactly 251 square submatrices.[6]
References
- ↑ Sloane, N. J. A., ed. "Sequence A005384 (Sophie Germain primes p: 2p+1 is also prime)". OEIS Foundation. https://oeis.org/A005384.
- ↑ Sloane, N. J. A., ed. "Sequence A006285 (Odd numbers not of form p + 2^x (de Polignac numbers))". OEIS Foundation. https://oeis.org/A006285.
- ↑ 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, ISBN 9780549210207, https://books.google.com/books?id=DirKAJqYGGsC&pg=PA14.
- ↑ Sloane, N. J. A., ed. "Sequence A008917 (Numbers that are the sum of 3 positive cubes in more than one way)". OEIS Foundation. https://oeis.org/A008917.
- ↑ De Koninck, Jean-Marie (2009), Those fascinating numbers, Providence, RI: American Mathematical Society, p. 64, ISBN 978-0-8218-4807-4, https://books.google.com/books?id=xdfTAwAAQBAJ&pg=PA64.
- ↑ Sloane, N. J. A., ed. "Sequence A030662 (Number of combinations of n things from 1 to n at a time, with repeats allowed)". OEIS Foundation. https://oeis.org/A030662.
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