Fatto generale: 21580 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21580 is an uninteresting number.
Trivia: 21580 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: January 30th is the day in 1858 that the first Hallé concert is given in Manchester, England, marking the official founding of the Hallé Orchestra as a full-time, professional orchestra.