A nuclear power station produces $16\ \text{MW}$ of electrical power. Its efficiency, from the energy released in fission to electrical energy, is $50\%$. Each fission of a uranium-235 nucleus releases $200\ \text{MeV}$. Take $1\ \text{MeV} = 1.6 \times 10^{-13}\ \text{J}$. If the number of fissions taking place each second is $N \times 10^{17}$, the value of N is ____.