Found with PFGW Version 3.7.5

873^7828-7828^873 is 2-PRP! (24.7716s+0.0026s)
873^7828-7828^873 is 3-PRP! (24.0620s+0.0022s)
873^7828-7828^873 is 5-PRP! (24.9243s+0.0020s)
873^7828-7828^873 is 7-PRP! (17.2643s+0.0017s)
873^7828-7828^873 is 11-PRP! (18.5751s+0.0017s)

Primality testing 873^7828-7828^873 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 3
Running N+1 test using discriminant 11, base 1+sqrt(11)
Calling N-1 BLS with factored part 0.04% and helper 0.01% (0.13% proof)
873^7828-7828^873 is Fermat and Lucas PRP! (126.2733s+0.0048s)

To be completed...