Belphegor's Prime

Interesting Number
Belphegor's prime is the palindromic prime:


 * $1000000000000066600000000000001$

It has:
 * $666$: the Number of the Beast in its center
 * Unlucky number $13$ zeroes either side of the $666$
 * $31$ digits, which is not only itself prime, but backwards is $13$ which is also prime.

The name Belphegor refers to one of the Seven Princes of Hell, whose particular specialty was helping people make ingenious inventions and discoveries.