Fait mathématique: 1601 is the number of forests with 12 vertices.
Culture générale: 1601 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: May 19th is the day in 1934 that Zveno and the Bulgarian Army engineer a coup d'état and install Kimon Georgiev as the new Prime Minister of Bulgaria.