general_fact: 4645 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 4645 is an unremarkable number.
trivia: 4645 is an unremarkable number.
historical_date: September 18th is the day in 324 that Constantine the Great decisively defeats Licinius in the Battle of Chrysopolis, establishing Constantine's sole control over the Roman Empire.