general_fact: 18681 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 18681 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 18681 is an unremarkable number.
historical_date: February 22nd is the day in 1889 that President Grover Cleveland signs a bill admitting North Dakota, South Dakota, Montana and Washington as U.S. states.