Primes / Is 431 prime?

Is 431 a Prime Number?

Yes

431 is prime: for 431, testing every prime up to √431 ≈ 20.8 (namely 2, 3, 5, 7, 11, 13, 17, 19) finds no divisor. 431 sits between primes 421 and 433, 10 below and 2 above. 431 shares no factor with 2-12; 431's divisors start beyond that range. 431 is odd, digit sum 8 for 431, digital root 8 for 431. 431 has 4 primes within 10 of 431.