general_fact: 18978 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 18978 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 18978 is a boring number.
historical_date: December 16th is the day in 1811 that the first two in a series of four severe earthquakes occur in the vicinity of New Madrid, Missouri.