Congruences in character tables of symmetric groups

If $\lambda$ and $\mu$ are two non-empty Young diagrams with the same number of squares, and $\boldsymbol\lambda$ and $\boldsymbol\mu$ are obtained by dividing each square into $d^2$ congruent squares, then the corresponding character value $\chi_{\boldsymbol\lambda}(\boldsymbol\mu)$ is divisible by $d!$.