Fait mathématique: 63973 is an uninteresting number.
Culture générale: 63973 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: February 24th is the day in 1999 that a China Southern Airlines Tupolev TU-154 airliner crashes on approach to Wenzhou airport in eastern the People's Republic of China, killing 61.