Fatto generale: 6444 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 6444 is the smallest number whose 5^{th} power starts with 5 identical digits.
Trivia: 6444 is a boring number.
Data storica: August 22nd is the day in 2004 that a version of The Scream and Madonna, two paintings by Edvard Munch, are stolen at gunpoint from a museum in Oslo, Norway.