Radix Sort takes $O(d*(n+b))$ time where $b$ is the base, $d$ is the numbers of digits present in the highest integer in the given range, and $n$ is the numbers of integers to be sorted.
Here, the maximum integer is $n^5-1$. So $d$, the number of digits is $O(log \; (n^5-1)) = O(log \; n)$. Value of $b$ is 10.
So overall time complexity is $O(log \; n * (n+10)) = O(n\; log\;n)$