general_fact: 21478 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21478 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 21478 is an uninteresting number.
historical_date: October 20th is the day in 1962 that China launches simultaneous offensives in Ladakh and across the McMahon Line, beginning the Sino-Indian War.