Primes / Is 251 prime?

Is 251 a Prime Number?

Yes

251 is prime: for 251, testing every prime up to √251 ≈ 15.8 (namely 2, 3, 5, 7, 11, 13) finds no divisor. 251 sits between primes 241 and 257, 10 below and 6 above. 251 shares no factor with 2-12; 251's divisors start beyond that range. 251 is odd, digit sum 8 for 251, digital root 8 for 251. 251 has 3 primes within 10 of 251.