general_fact: 21718 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21718 is a boring number.
trivia: 21718 is an uninteresting number.
historical_date: June 17th is the day in 1960 that the Nez Perce tribe is awarded $4 million for 7 million acres (28,000 km2) of land undervalued at 4 cents/acre in the 1863 treaty.