math_fact: 5142 is the sum of its proper divisors that contain the digit 7.
trivia: 5142 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: January 28th is the day in 1964 that an unarmed USAF T-39 Sabreliner on a training mission is shot down over Erfurt, East Germany, by a Soviet MiG-19.