Electromagnetic radiation of wavelength 663 nm is just sufficient to ionise the atom of metal A. The ionization enegy of metal A in kJ mol^$-$1 is __________. (Rounded off to the nearest integer)

[h = 6.63 $\times$ 10^$-$34 Js, c = 3.00 $\times$ 10⁸ ms^$-$1, N_A = 6.02 $\times$ 10²³ mol^$-$1]