Hecho general: 21718 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 21718 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 21718 is an uninteresting number.
Fecha histórica: June 17th is the day in 1948 that a Douglas DC-6 carrying United Airlines Flight 624 crashes near Mount Carmel, Pennsylvania, killing all 43 people on board.