Fatto generale: 64439 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 64439 is an unremarkable number.
Trivia: 64439 is an unremarkable number.
Data storica: June 4th is the day in 1920 that Hungary loses 71% of its territory and 63% of its population when the Treaty of Trianon is signed in Paris.