Fatto generale: 20543 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20543 is a boring number.
Trivia: 20543 is an uninteresting number.
Data storica: March 29th is the day in 1990 that the Czechoslovak parliament is unable to reach an agreement on what to call the country after the fall of Communism, sparking the so-called Hyphen War.