Hecho general: 403 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 403 is the product of two primes which are reverses of each other.
Trivia: 403 is a boring number.
Fecha histórica: February 6th is the day in 1649 that the claimant King Charles II of England and Scotland is declared King of Great Britain, by the Parliament of Scotland.