Is that right?
Not quite.
I believe the internal resistors are 20k? or is that just the pullups?
That only applies when the pull up resistor is enabled. Normally an input is a much higher impedance. The data sheet specifies this as leakage current with 5.5V on the pin, at 1uA. You also have a diode so you need to take into account the reverse bias leakage current as well, so in total I would be surprise at more than a few uA.