General fact: 1558 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 1558 is an unremarkable number.
Trivia: 1558 is a boring number.
Historical date: April 6th is the day in 1994 that the Rwandan Genocide begins when the aircraft carrying Rwandan president Juvénal Habyarimana and Burundian president Cyprien Ntaryamira is shot down.