A centillion is an extremely large number, equal to 10^303 in the short scale or 10^600 in the long scale.
Assuming you could count one number per second without stopping, it would take approximately 3.17 x 10^292 years to count to a centillion. This is an incomprehensibly long time, considering that the current age of the universe is estimated to be around 13.8 billion years.
It is impossible for a person to count to a centillion, as it would require an unfeasible amount of time and stamina.