Mathematical fact: 2663 is the number of digits of the 20^{th} perfect number.
Trivia: 2663 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: April 16th is the day in 1919 that Gandhi organizes a day of "prayer and fasting" in response to the killing of Indian protesters in the Amritsar Massacre by the British.