Fatto matematico: 773 is the smallest odd number n so that n+2^{k} is composite for all k<n.
Trivia: 773 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: February 11th is the day in 1855 that Kassa Hailu is crowned Tewodros II, Emperor of Ethiopia, by Abuna Salama III in a ceremony at the church of Derasge Maryam.