general_fact: 15170 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 15170 is an uninteresting number.
trivia: 15170 is an uninteresting number.
historical_date: July 13th is the day in 1973 that Alexander Butterfield reveals the existence of the "Nixon tapes" to the special Senate committee investigating the Watergate break in.