Primality proof for n = 12227:

Take b = 2.

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

6113 is prime.
b^((n-1)/6113)-1 mod n = 3, which is a unit, inverse 4076.

(6113) divides n-1.

(6113)^2 > n.

n is prime by Pocklington's theorem.