general_fact: 21289 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21289 is an unremarkable number.
trivia: 21289 is an uninteresting number.
historical_date: April 14th is the day in 1999 that NATO mistakenly bombs a convoy of ethnic Albanian refugees – Yugoslav officials say 75 people are killed.