Fait général: 4621 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 4621 is p(4×6×2×1×(4+6+2+1)).
Culture générale: 4621 is an uninteresting number.
Date historique: August 25th is the day in 1537 that the Honourable Artillery Company, the oldest surviving regiment in the British Army, and the second most senior, is formed.