Primes / Is 397 prime?

Is 397 a Prime Number?

Yes

397 is prime: for 397, testing every prime up to √397 ≈ 19.9 (namely 2, 3, 5, 7, 11, 13, 17, 19) finds no divisor. 397 sits between primes 389 and 401, 8 below and 4 above. 397 shares no factor with 2-12; 397's divisors start beyond that range. 397 is odd, digit sum 19 for 397, digital root 1 for 397. 397 has 3 primes within 10 of 397.