Found with PFGW Version 3.7.5

4489^8720-8720^4489 is 2-PRP! (18.0019s+0.0014s)
4489^8720-8720^4489 is 3-PRP! (18.1469s+0.0014s)
4489^8720-8720^4489 is 5-PRP! (19.8384s+0.0014s)
4489^8720-8720^4489 is 7-PRP! (17.7211s+0.0012s)
4489^8720-8720^4489 is 11-PRP! (17.7277s+0.0014s)

Primality testing 4489^8720-8720^4489 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 3
Running N+1 test using discriminant 7, base 1+sqrt(7)
Calling N+1 BLS with factored part 0.02% and helper 0.01% (0.08% proof)
4489^8720-8720^4489 is Fermat and Lucas PRP! (103.1823s+0.0023s)

To be completed...