Fait général: 1551 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 1551 is the number of trees on 25 vertices with diameter 4.
Culture générale: 1551 is a boring number.
Date historique: March 30th is the day in 1981 that President Ronald Reagan is shot in the chest outside a Washington, D.C., hotel by John Hinckley, Jr.