Primality proof for n = 2089:
Take b = 3.
b^(n-1) mod n = 1.
29 is prime.
b^((n-1)/29)-1 mod n = 31, which is a unit, inverse 1213.
3 is prime.
b^((n-1)/3)-1 mod n = 825, which is a unit, inverse 1813.
(3^2 * 29) divides n-1.
(3^2 * 29)^2 > n.
n is prime by Pocklington's theorem.