Fatto generale: 16213 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 16213 is an uninteresting number.
Trivia: 16213 is an uninteresting number.
Data storica: May 21st is the day in 1936 that Sada Abe is arrested after wandering the streets of Tokyo for days with her dead lover's severed genitals in her hand.