math_fact: 1559 is the smallest prime p with 16 consecutive quadratic residues mod p.
trivia: 1559 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: April 7th is the day in 1999 that the World Trade Organization rules in favor of the United States in its long-running trade dispute with the European Union over bananas.