Fatto generale: 21069 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21069 is an unremarkable number.
Trivia: 21069 is a boring number.
Data storica: September 6th is the day in 1991 that the name Saint Petersburg is restored to Russia's second largest city, which had been renamed Leningrad in 1924.