Primality proof for n = 2151858718037429125511251:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=20387630040577.html>20387630040577 is prime.</a>
<br>b^((n-1)/20387630040577)-1 mod n = 1609459712269279077779375, which is a unit, inverse 72744713369542696959983.
<p>(20387630040577) divides n-1.
<p>(20387630040577)^2 > n.
<p>n is prime by Pocklington's theorem.