Primality proof for n = 3878713:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=17957.html>17957 is prime.</a>
<br>b^((n-1)/17957)-1 mod n = 2727979, which is a unit, inverse 2272558.
<p>(17957) divides n-1.
<p>(17957)^2 > n.
<p>n is prime by Pocklington's theorem.