Fatto generale: 1551 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1551 is the number of trees on 25 vertices with diameter 4.
Trivia: 1551 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: March 30th is the day in 1867 that Alaska is purchased from Russia for $7.2 million, about 2 cent/acre ($4.19/km²), by United States Secretary of State William H. Seward.