How do I find mass equivalence of a photon? The problem has a flame emitting a wavelength of $589\ \mathrm{nm}$, and asks for the mass of one photon of that wavelength. It tells me that $1\ \mathrm J = 1\ \frac{\mathrm{kg\cdot m^2}}{\mathrm s^2}$.


I converted to $\mathrm J$ using $E=\frac{h\cdot c}{\lambda}$. I'm not quite sure what to do past that. I have $3.36\cdot 10^{-19}\mathrm J$. I know the answer is supposed to be $3.75\cdot 10^{-34}$.
$$E = \frac{h\cdot c}{\lambda}$$

$$1\ \mathrm J = 6.24150934 \times 10^{18}\ \mathrm{eV}$$

then you have 
$$E = mc^2 = \frac{h\cdot c}{\lambda}$$