Primality proof for n = 3969899:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=104471.html>104471 is prime.</a>
<br>b^((n-1)/104471)-1 mod n = 2100183, which is a unit, inverse 2243650.
<p>(104471) divides n-1.
<p>(104471)^2 > n.
<p>n is prime by Pocklington's theorem.