Wolstenholme's theorem states that any prime $p > 3$ satisfies $\binom{2p-1}{p-1} \equiv 1 (\pmod{p^3})$.
Formal proof linked here provided by AlphaProof. Reference: Wikipedia
Two known Wolstenholme primes: 16843 and 2124679.
Formal proof linked here provided by AlphaProof
Equivalently, a prime $p > 7$ is a Wolstenholme prime if it divides the numerator of the Bernoulli number $B_{p-3}$.
It is conjectured that there are infinitely many Wolstenholme primes.
Reference: Wikipedia