Primality proof for n = 87433:

Take b = 2.

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

3643 is prime.
b^((n-1)/3643)-1 mod n = 77512, which is a unit, inverse 48286.

(3643) divides n-1.

(3643)^2 > n.

n is prime by Pocklington's theorem.