Primality proof for n = 1390586390785817:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=3986498609.html>3986498609 is prime.</a>
<br>b^((n-1)/3986498609)-1 mod n = 289137438737830, which is a unit, inverse 869790696162686.
<p>(3986498609) divides n-1.
<p>(3986498609)^2 > n.
<p>n is prime by Pocklington's theorem.