Fatto matematico: 6455 is the smallest value of n for which the n^{th} prime begins with the digits of n.
Trivia: 6455 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: September 2nd is the day in 421 that Emperor Constantius III dies suddenly of an illness, his wife Galla Placidia becomes for the second time widow.