general_fact: 18488 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 18488 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 18488 is an uninteresting number.
historical_date: August 13th is the day in 1979 that the roof of the uncompleted Rosemont Horizon near Chicago, Illinois collapses, killing 5 workers and injuring 16.