The prime factors of 7!7!7! (7 factorial) are:
2,3,5,72, 3, 5, 72,3,5,7
1,2,3,4,5,6,71, 2, 3, 4, 5, 6, 71,2,3,4,5,6,7
2,3,52, 3, 52,3,5
777 only