Fatto generale: 8219 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 8219 is a value of n for which 4n and 5n together use each digit exactly once.
Trivia: 8219 is an uninteresting number.
Data storica: July 2nd is the day in 1966 that the French military explodes a nuclear test bomb codenamed Aldébaran in Mururoa, their first nuclear test in the Pacific.