Take b = 2.

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

139 is prime.

b^((n-1)/139)-1 mod n = 28814, which is a unit, inverse 5870.

37 is prime.

b^((n-1)/37)-1 mod n = 7871, which is a unit, inverse 10813.

(37 * 139) divides n-1.

(37 * 139)^2 > n.

n is prime by Pocklington's theorem.