general_fact: 15683 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 15683 is an unremarkable number.
trivia: 15683 is a boring number.
historical_date: December 8th is the day in 1972 that United Airlines Flight 553 crashes after aborting its landing attempt at Chicago Midway International Airport, killing 45.