Found with PFGW Version 3.7.5

3621^10720-10720^3621 is 2-PRP! (26.7855s+0.0015s)
3621^10720-10720^3621 is 3-PRP! (26.5734s+0.0014s)
3621^10720-10720^3621 is 5-PRP! (26.9042s+0.0015s)
3621^10720-10720^3621 is 7-PRP! (27.1161s+0.0014s)
3621^10720-10720^3621 is 11-PRP! (26.7121s+0.0016s)

Primality testing 3621^10720-10720^3621 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 3
Running N-1 test using base 7
Running N+1 test using discriminant 17, base 8+sqrt(17)
Calling N-1 BLS with factored part 0.06% and helper 0.03% (0.21% proof)
3621^10720-10720^3621 is Fermat and Lucas PRP! (187.1456s+0.0027s)

To be completed...