Primality proof for n = 8111:

Take b = 2.

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

811 is prime.
b^((n-1)/811)-1 mod n = 1023, which is a unit, inverse 8000.

(811) divides n-1.

(811)^2 > n.

n is prime by Pocklington's theorem.