Primality proof for n = 4271386466502519123378319257166758282929862876911918307708639947947974242171:

Take b = 2.

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

114430077720284863765762092766225391679591020381 is prime.
b^((n-1)/114430077720284863765762092766225391679591020381)-1 mod n = 3857113039832290054245130548565264413284219145046729770236118055172338740335, which is a unit, inverse 3960258871456578813736377485796096493871051875319989041101422325388252919155.

(114430077720284863765762092766225391679591020381) divides n-1.

(114430077720284863765762092766225391679591020381)^2 > n.

n is prime by Pocklington's theorem.