CODE 21** Problem with oxygen sensor signal circuit.Sensor voltage to computer not fluctuating.
CODE 32** An open or shorted condition detected in the EGR solenoid circuit.Possible air/fuel ratio imbalance not detected during diagnosis.
I don't see anything about a code 64 in the book. Is it possible that the last code was 55 and not 64. Becouse 55 means that the codes are done (end of codes code).
My guess is that the Upstream 02 sensor on your exhaust manifold is bad. The one on the pipe behind the cat (if your car has one) is the downstream 02 sensor. It should have nothing to do with these codes. However the upstream sensor may just be the cause of both codes, not only will it solve the code 21 it should also solve code 32.
The 02 sensor causes a air/fuel ratio imbalance and then the imbalance is noticed by the EGR.Good luck!