Primality proof for n = 30773:

Take b = 2.

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

157 is prime.
b^((n-1)/157)-1 mod n = 18481, which is a unit, inverse 10377.

2 is prime.
b^((n-1)/2)-1 mod n = 30771, which is a unit, inverse 15386.

(2^2 * 157) divides n-1.

(2^2 * 157)^2 > n.

n is prime by Pocklington's theorem.