general_fact: 21720 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21720 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 21720 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: June 19th is the day in 1987 that Basque separatist group ETA commits one of its most violent attacks, in which a bomb is set off in a supermarket, Hipercor, killing 21 and injuring 45.