Primality proof for n = 323131:

Take b = 2.

b^(n-1) mod n = 1.

10771 is prime.
b^((n-1)/10771)-1 mod n = 300641, which is a unit, inverse 34497.

(10771) divides n-1.

(10771)^2 > n.

n is prime by Pocklington's theorem.