It would be surprising if the Earth was a perfect sphere and indeed, its not, so the “radius” changes. The Earth is flatter at the poles and as a result the weight of a given person at the north or south pole increases slightly.
The other guys answered this one well so I will just try to add a fun fact. Because the Earths radius varies as you go from the equator to the poles then the strength of gravity also varies. And since Einstein tells us that time travels at different rates for different strengths of gravity then people who live at the poles feel time travelling slower than people who live at the equator. The difference is very small but it is there. In fact if you spend some time up a high building then time will be going slightly faster for you than for the rest of us. You are then kind of travelling back in time relative to the rest of us!