Primality proof for n = 13928737:

Take b = 2.

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

145091 is prime.
b^((n-1)/145091)-1 mod n = 72827, which is a unit, inverse 862573.

(145091) divides n-1.

(145091)^2 > n.

n is prime by Pocklington's theorem.