1221

1221 = 3 x 11 x 37.

1221 is a number that can be expressed as the product of numbers made of only one digit: 1221 = 11 x 111.

1221 is a divisor of 100³ - 1.

1221 is a number of the form n² - 4, for n = 35.

1221 is 14341 (palindromic) in base 5. 1221 is 5353 in base 6, 3363 in base 7, and 633 in base 14,

In the palindromic year 1221, the Maya of the Yucatán revolted against the rulers of Chichen Itza and Holy Roman Emperor Frederick II founded the University of Padua in Italy.

Source: Wikipedia