251 (number)

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

← 250 251 252 →
← 250 251 252 253 254 255 256 257 258 259 → List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred fifty-one
Ordinal	251st (two hundred fifty-first)
Factorization	prime
Prime	54th
Greek numeral	ΣΝΑ´
Roman numeral	CCLI, ccli
Binary	111110112
Ternary	1000223
Senary	10556
Octal	3738
Duodecimal	18B12
Hexadecimal	FB16

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.^[2]
• 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.^[3][4]
• the smallest number that can be formed in more than one way by summing three positive cubes:^[5][6]${\displaystyle 251=2^{3}+3^{3}+6^{3}=1^{3}+5^{3}+5^{3}.}$

Every 5 × 5 matrix has exactly 251 square submatrices.^[7]