A perfectly reflecting mirror of mass M mounted on a spring constitutes a spring-mass system of angular frequency  Ω such that  4πMΩh=1024m−2 with h as Planck’s constant. N photons of wavelength  λ=8π×10−6m strike the mirror simultaneously at normal incidence such that the mirror gets displaced by 1μm . If the value of N is   x ×1012, then the value of x is ______[Consider the spring as massless]