Fait mathématique: 8631 is a value of n for which 3n and 7n together use each digit exactly once.
Culture générale: 8631 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: August 18th is the day in 1977 that Steve Biko is arrested at a police roadblock under the Terrorism Act No 83 of 1967 in King William's Town, South Africa.