Primality proof for n = 50711861:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=3919.html>3919 is prime.</a>
<br>b^((n-1)/3919)-1 mod n = 49876571, which is a unit, inverse 28475661.
<p><a href=647.html>647 is prime.</a>
<br>b^((n-1)/647)-1 mod n = 41583436, which is a unit, inverse 34551630.
<p>(647 * 3919) divides n-1.
<p>(647 * 3919)^2 > n.
<p>n is prime by Pocklington's theorem.