Are there any activation functions which on inputting integer data will produce the output as integers?
There are quite a lot of activation functions $f : \mathbb{R} \rightarrow \mathbb{R}$ such that their restriction to integers $f|_\mathbb{Z} : \mathbb{Z} \rightarrow \mathbb{Z}$ produce integer values. $f(x) = max\{0,x\}$ is quite famous.