Fait mathématique: 98639 is an uninteresting number.
Culture générale: 98639 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: January 23rd is the day in 1510 that Henry VIII of England, then 18 years old, appears incognito in the lists at Richmond, and is applauded for his jousting before he reveals his identity.