Apéry's constant is a mathematical constant denoted by \( \zeta(3) \), and it is defined as the value of the Riemann zeta function at \( s = 3 \): \[ \zeta(3) = \sum_{n=1}^\infty \frac{1}{n^3} \] This series converges to a specific numerical value, approximately \( 1.2020569 \).