Take b = 2.

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

124769 is prime.

b^((n-1)/124769)-1 mod n = 1253283114, which is a unit, inverse 11990557020.

15383 is prime.

b^((n-1)/15383)-1 mod n = 21490604189, which is a unit, inverse 8627286916.

(15383 * 124769) divides n-1.

(15383 * 124769)^2 > n.

n is prime by Pocklington's theorem.