The number of photons falling per second on a completely darkened plate to produce a force of $6.62 \times 10^{-5}$ N is $n$. If the wavelength of the light falling is $5 \times 10^{-7}$ m, then $n = \_\_\_$ × $10^{22}$. (Planck's constant, $h = 6.62 \times 10^{-34}$ J·s)