Fatto matematico: 4687 is a value of n for which s(f(n)) = 3s(n).
Trivia: 4687 is an unremarkable number.
Data storica: October 30th is the day in 1226 that Tran Thu Do, head of the Tran clan of Vietnam, forces Ly Hue Tong, the last emperor of the Ly dynasty, to commit suicide.