  In this paper we analyze the capacitary potential due to a charged body in
order to deduce sharp analytic and geometric inequalities, whose equality cases
are saturated by domains with spherical symmetry. In particular, for a regular
bounded domain $\Omega \subset \mathbb{R}^n$, $n\geq 3$, we prove that if the
mean curvature $H$ of the boundary obeys the condition $$ - \bigg[
\frac{1}{\text{Cap}(\Omega)} \bigg]^{\frac{1}{n-2}} \leq \frac{H}{n-1} \leq
\bigg[ \frac{1}{\text{Cap}(\Omega)} \bigg]^{\frac{1}{n-2}} , $$ then $\Omega$
is a round ball.
