Fatto generale: 4655 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 4655 is the number of 10-ominoes.
Trivia: 4655 is an uninteresting number.
Data storica: September 28th is the day in 1939 that Nazi Germany and the Soviet Union agree on a division of Poland after their invasion during World War II.