Primes / Is 523 prime?

Is 523 a Prime Number?

Yes

523 is prime: for 523, testing every prime up to √523 ≈ 22.9 (namely 2, 3, 5, 7, 11, 13, 17, 19) finds no divisor. 523 sits between primes 521 and 541, 2 below and 18 above. 523 shares no factor with 2-12; 523's divisors start beyond that range. 523 is odd, digit sum 10 for 523, digital root 1 for 523. 523 has 2 primes within 10 of 523.