Found with PFGW Version 3.6.0

2121^3812-3812^2121 is 2-PRP! (6.6365s+0.0017s)
2121^3812-3812^2121 is 3-PRP! (6.6163s+0.0035s)
2121^3812-3812^2121 is 5-PRP! (6.6031s+0.0020s)
2121^3812-3812^2121 is 7-PRP! (6.6451s+0.0019s)
2121^3812-3812^2121 is 11-PRP! (6.5884s+0.0020s)

Primality testing 2121^3812-3812^2121 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 7
Running N+1 test using discriminant 13, base 8+sqrt(13)
Calling N-1 BLS with factored part 0.05% and helper 0.02% (0.18% proof)
2121^3812-3812^2121 is Fermat and Lucas PRP! (30.7080s+0.0017s)

To be completed...