general_fact: 2551 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 2551 is an uninteresting number.
trivia: 2551 is an uninteresting number.
historical_date: December 25th is the day in 2007 that a tiger at the San Francisco Zoo escapes from its enclosure and attacks three people, killing one.