Fatto generale: 66990 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 66990 is an unremarkable number.
Trivia: 66990 is an unremarkable number.
Data storica: May 30th is the day in 1416 that the Council of Constance, called by the Emperor Sigismund, a supporter of Antipope John XXIII, burns Jerome of Prague following a trial for heresy.