Fait général: 20565 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 20565 is an unremarkable number.
Culture générale: 20565 is an uninteresting number.
Date historique: April 20th is the day in 1918 that Manfred von Richthofen, aka The Red Baron, shoots down his 79th and 80th victims, his final victories before his death the following day.