Fatto matematico: 4257 is the number of triangles formed by connecting the diagonals of a regular 11-gon.
Trivia: 4257 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: August 27th is the day in 1985 that the Nigerian government is peacefully overthrown by Army Chief of Staff Major General Ibrahim Babangida.