Short Answer let T(n) be time complexity of function then O($n^{5}) \leq T(n) \leq \Omega (n)$
Brief answer:
For each iteration of outer most loop (i$^{th}$ loop) the inner loop (j$^{th}$ loop and k$^{th}$ loop) will execute i$^{2}$ times
we can summarize it as $\sum_{i=1}^{n} \frac{i^{2}*(i^{2}+1)}{2}$
$\sum_{i=1}^{n} \frac{i^{4}+i^{2}}{2}$
$\sum_{i=1}^{n} \frac{i^{2}}{2}+\sum_{i=1}^{n} \frac{i^{4}}{2}$
Final equation will be
$\left [ \frac{6n^{5}+15n^{4}+20n^{3}+15n^{2}+4n}{60} \right ]$