general_fact: 21746 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21746 is an unremarkable number.
trivia: 21746 is a boring number.
historical_date: July 15th is the day in 1381 that John Ball, a leader in the Peasants' Revolt, is hanged, drawn and quartered in the presence of King Richard II of England.