Primality proof for n = 161839:
<p>Take b = 3.
<p>b^(n-1) mod n = 1.
<p><a href=37.html>37 is prime.</a>
<br>b^((n-1)/37)-1 mod n = 153493, which is a unit, inverse 136262.
<p><a href=3.html>3 is prime.</a>
<br>b^((n-1)/3)-1 mod n = 137081, which is a unit, inverse 62198.
<p>(3^7 * 37) divides n-1.
<p>(3^7 * 37)^2 > n.
<p>n is prime by Pocklington's theorem.