general_fact: 18735 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 18735 is an unremarkable number.
trivia: 18735 is an unremarkable number.
historical_date: April 17th is the day in 1492 that Spain and Christopher Columbus sign the Capitulations of Santa Fe for his voyage to Asia to acquire spices.