Fatto matematico: 2557 is the number of proper divisors of the 15^{th} perfect number.
Trivia: 2557 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: December 31st is the day in 1955 that the General Motors Corporation becomes the first U.S. corporation to make over US$1 billion in a year.