Primality proof for n = 4447:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=19.html>19 is prime.</a>
<br>b^((n-1)/19)-1 mod n = 1435, which is a unit, inverse 595.
<p><a href=13.html>13 is prime.</a>
<br>b^((n-1)/13)-1 mod n = 2671, which is a unit, inverse 318.
<p>(13 * 19) divides n-1.
<p>(13 * 19)^2 > n.
<p>n is prime by Pocklington's theorem.