Fatto generale: 21972 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21972 is a boring number.
Trivia: 21972 is a boring number.
Data storica: February 26th is the day in 1920 that the first German Expressionist film and early horror movie, Robert Wiene's The Cabinet of Dr. Caligari, premièred in Berlin.