The atomic number of the element next to Sulphur in the same group is

The electronic configuration ofS is $\left(1s{)}^2\right(2s{)}^2\left(2p{)}^6\right(3s{)}^2(3p{)}^4$.

So the next element in this group will have configuration

$\left(1s{)}^2\right(2s{)}^2\left(2p{)}^6\right(3s{)}^2\left(3p{)}^6\right(3\mathrm{d}{)}^{10}\left(4s{)}^2\right(4p{)}^4$

that is, its atomic number is 34.