Fatto generale: 21009 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21009 is an unremarkable number.
Trivia: 21009 is a boring number.
Data storica: July 8th is the day in 1808 that Joseph Bonaparte approves the Bayonne Statute, a royal charter intended as the basis for his rule as king of Spain.