If the work function of a metal is 6.63 × 10^-19 J, the maximum wavelength of the photon required to remove a photoelectron from the metal is \ \ \ \…

If the work function of a metal is $\displaystyle 6.63 \times 10^{-19} \mathrm{~J}$, the maximum wavelength of the photon required to remove a photoelectron from the metal is \_\_\_\_ nm. (Nearest integer) [Given : $\displaystyle \mathrm{h}=6.63 \times 10^{-34} \mathrm{~J} \mathrm{~s}$, and $\displaystyle \mathrm{c}=3 \times 10^8 \mathrm{~m} \mathrm{~s}^{-1}$ ]