Fatto generale: 1525 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1525 is a value of n for which s(f(n)) = 2s(n).
Trivia: 1525 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: March 4th is the day in 1985 that the Food and Drug Administration approves a blood test for AIDS, used since then for screening all blood donations in the United States.