Primality proof for n = 3986498609:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=1033843.html>1033843 is prime.</a>
<br>b^((n-1)/1033843)-1 mod n = 3868493676, which is a unit, inverse 1333074980.
<p>(1033843) divides n-1.
<p>(1033843)^2 > n.
<p>n is prime by Pocklington's theorem.