Found with PFGW Version 3.7.5

7640^8571-8571^7640 is 2-PRP! (22.1805s+0.0015s)
7640^8571-8571^7640 is 3-PRP! (21.5294s+0.0016s)
7640^8571-8571^7640 is 5-PRP! (22.4156s+0.0015s)
7640^8571-8571^7640 is 7-PRP! (21.4555s+0.0015s)
7640^8571-8571^7640 is 11-PRP! (21.6578s+0.0015s)

Primality testing 7640^8571-8571^7640 [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)
Calling N+1 BLS with factored part 0.05% and helper 0.02% (0.18% proof)
7640^8571-8571^7640 is Fermat and Lucas PRP! (106.5316s+0.0024s)

To be completed...