Hecho general: 53221 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 53221 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 53221 is an uninteresting number.
Fecha histórica: September 17th is the day in 1908 that the Wright Flyer flown by Orville Wright, with Lieutenant Thomas Selfridge as passenger, crashes killing Selfridge.