The retina of the eye contains two types of light sensitive cells: rods (responsible for night vision) and cones (responsible for color vision). Rod cells are about a hundred times more sensitive to light than cone cells and are able to detect a single photon. Suppose a group of rod cells are radiated with a pulse of light having an energy equal to 1.60 × 10^-16 J. If the wavelength of this light was 498 nm (the wavelength at which rod cells are most sensitive), how many photons are in this light pulse?