Non-inverting OP Amp supply
To get an output voltage of 4.2V, your supply should be at least 5V.  The output of the opamp cannot be higher than its rail voltage (and you won't even get that much out, even with a rail-to-rail type).

Further, with an input voltage of 0.54mV, you are going to have no luck with such a simple circuit.  You will also need a negative supply with inputs that close to ground.