Fatto generale: 20564 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20564 is a boring number.
Trivia: 20564 is an uninteresting number.
Data storica: April 19th is the day in 1919 that Leslie Irvin of the United States makes the first successful voluntary free-fall parachute jump using a new kind of self-contained parachute.