Fait mathématique: 4631 is an unremarkable number.
Culture générale: 4631 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: September 4th is the day in 1260 that the Sienese Ghibellines, supported by the forces of King Manfred of Sicily, defeat the Florentine Guelphs at Montaperti.