Ok, For each i , j loop runs N/i times.
Example for i = 5 ,
It will run 1 , 6 , 11 , 16 , 21 means( N/5 )
Hence overall : N/1 + N/2 + N/3 + N/4 ..... N/N.
$=N \left(1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \dots + \frac{1}{n}\right)$
$= \Theta(N \log N)$ (Sum to N term of Harmonic series is $\Theta \left(N \log N\right)$