Primality proof for n = 3346351:
Take b = 2.
b^(n-1) mod n = 1.
3187 is prime. b^((n-1)/3187)-1 mod n = 740744, which is a unit, inverse 3060304.
(3187) divides n-1.
(3187)^2 > n.
n is prime by Pocklington's theorem.