Primality proof for n = 127727:
Take b = 2.
b^(n-1) mod n = 1.
63863 is prime. b^((n-1)/63863)-1 mod n = 3, which is a unit, inverse 42576.
(63863) divides n-1.
(63863)^2 > n.
n is prime by Pocklington's theorem.