Fatto generale: 2920 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 2920 is a heptagonal pyramidal number.
Trivia: 2920 is a boring number.
Data storica: December 29th is the day in 1911 that Sun Yat-sen becomes the provisional President of the Republic of China; he formally takes office on January 1, 1912.