General fact: 356 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 356 is the smallest happy number of height 6.
Trivia: 356 is a boring number.
Historical date: December 21st is the day in 1946 that an 8.1 Mw earthquake and subsequent tsunami in Nankaidō, Japan, kill over 1,300 people and destroy over 38,000 homes.