general_fact: 28391 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 28391 is an uninteresting number.
trivia: 28391 is a boring number.
historical_date: September 23rd is the day in 1845 that the Knickerbockers Baseball Club, the first baseball team to play under the modern rules, is founded in New York.