Fait mathématique: 20397 is an unremarkable number.
Culture générale: 20397 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: November 4th is the day in 1993 that a China Airlines Boeing 747 overruns Runway 13 at Hong Kong's Kai Tak International Airport while landing during a typhoon, injuring 22 people.