Periodic Table And Periodicity

If first ionisation enthalpy $\left(\Delta_{i} H\right)$ values of $\mathrm{Na}, \mathrm{Mg}$ and Si are respectively 496,737 and $786 \mathrm{~kJ} \mathrm{~mol}^{-1}$, the first ionisation enthalpy value of $\mathrm{Al}\left(\mathrm{in} \mathrm{kJ} \mathrm{mol}^{-1}\right.$ ) will be