Fatto generale: 6427 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 6427 is the number of ways a 6×6 square can be tiled with 1×1 and 2×2 squares.
Trivia: 6427 is a boring number.
Data storica: August 5th is the day in 2003 that a car bomb explodes in the Indonesian capital of Jakarta outside the Marriott Hotel killing 12 and injuring 150.