If \( [\mathrm{Cu(H_2O)_4}]^{2+} \) absorbs a light of wavelength \( 600 \, \text{nm} \) for d-d transition, then the value of octahedral crystal field splitting energy for \( [\mathrm{Cu(H_2O)_6}]^{2+} \) will be __________ \( \times 10^{-21} \, \text{J} \). (Nearest Integer)
[Given : \( h = 6.63 \times 10^{-34} \, \text{J s} \) and \( c = 3.08 \times 10^{8} \, \text{m s}^{-1} \) ]