general_fact: 21229 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21229 is an unremarkable number.
trivia: 21229 is an uninteresting number.
historical_date: February 13th is the day in 2004 that the Harvard-Smithsonian Center for Astrophysics announces the discovery of the universe's largest known diamond, white dwarf star BPM 37093.