Fatto generale: 6466 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 6466 is the largest known value of n for which the n^{th} prime begins with the digits of n.
Trivia: 6466 is an unremarkable number.
Data storica: September 13th is the day in 585 BC that Lucius Tarquinius Priscus, king of Rome, celebrates a triumph for his victories over the Sabines, and the surrender of Collatia.