Primality proof for n = 26711:

Take b = 2.

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

2671 is prime.
b^((n-1)/2671)-1 mod n = 1023, which is a unit, inverse 4491.

(2671) divides n-1.

(2671)^2 > n.

n is prime by Pocklington's theorem.