(5379919 spells 'GIGGLES' when turned upside down on a calculator.)

PFGW Version 1.2.0 for Windows [FFT v23.8]

Primality testing 10^12878+5379919
[N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 7
Running N+1 test using discriminant 13, base 1+sqrt(13)
10^12878+5379919 is Fermat and Lucas PRP!

To be completed...