I bet you meant "consecutive". If x is the smallest of the 5 numbers, then the other 4 are x + 1, x + 2, x + 3, and x + 4. If their mean is 11, then
(x + (x + 1) + (x + 2) + (x + 3) + (x + 4))/5
= (5x + 10)/5
= x + 2 = 11
==> x = 9
Then the five numbers are {9, 10, 11, 12, 13}.
Alternatively, since we're talking about an odd number of consecutive integers, the mean among them will always be the number in the middle. So if 11 is the mean, and there are five numbers overall, then we just take the four closest integers to 11, two on either side.