Fatto generale: 1581 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1581 is the smallest number whose 8^{th} power contains exactly the same digits as another 8^{th} power.
Trivia: 1581 is an unremarkable number.
Data storica: April 29th is the day in 1483 that Gran Canaria, the main of the Canary Islands is conquered by the Kingdom of Castile, very important step in the expansion of Spain.