Primality proof for n = 4156739:

Take b = 2.

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

683 is prime.
b^((n-1)/683)-1 mod n = 259617, which is a unit, inverse 2477805.

179 is prime.
b^((n-1)/179)-1 mod n = 2368194, which is a unit, inverse 2699056.

(179 * 683) divides n-1.

(179 * 683)^2 > n.

n is prime by Pocklington's theorem.