1111 = 11 x 101.
1111 is the sum of the digits of the first 100 primes.
1111 is a number that cannot be written as a sum of three squares.
1111 is a divisor of 1002 - 1.
1111 is n3 + n2 + n + 1, for n = 10.
1111 is 787 in base 12.
Armistice Day, Nov. 11 (11/11), is the anniversary of the symbolic end of World War I in 1918, when the leaders of several countries signed an agreement on the 11th hour of the 11th day of the 11th month to cease hostilities.
Source: Number Gossip