Primality proof for n = 20705423504133292078628634597817:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=862725979338887169942859774909.html>862725979338887169942859774909 is prime.</a>
<br>b^((n-1)/862725979338887169942859774909)-1 mod n = 16777215, which is a unit, inverse 9528120837126448207374882683518.
<p>(862725979338887169942859774909) divides n-1.
<p>(862725979338887169942859774909)^2 > n.
<p>n is prime by Pocklington's theorem.