1911

1911 = 3 x 7 x 7 x 13.

1911 is 11101110111 in base 2 (binary) (A023691), 131313 in base 4 (A037576), and 1133 in base 12 (A033010). It is 876 in base 15 and 777 in base 16 (A033029).

1911 is a hendecadonal number (A051682). It is also a heptagonal pyramidal number (A002413).

1911 divides 79³ - 1.

1911 was a year with exactly two "Friday the 13ths" (A190652).

Source: What's Special About This Number?