Primality proof for n = 133087:

Take b = 2.

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

541 is prime.
b^((n-1)/541)-1 mod n = 67137, which is a unit, inverse 18612.

(541) divides n-1.

(541)^2 > n.

n is prime by Pocklington's theorem.