general_fact: 56723 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 56723 is an unremarkable number.
trivia: 56723 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: April 20th is the day in 1865 that Astronomer Pietro Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX's yacht, the L’Immaculata Concezion.