  Nonrelativistic and relativistic coupled-cluster calculations extrapolated to
the complete basis set limit including excitations up to the quintuple level
(CCSDTQP) were carried out to accurately determine the static electric dipole
polarizability of the closed-shell palladium atom. The resulting value of
$\alpha$ = 26.14(10) a.u. implies that palladium has the smallest dipole
polarizability of all known elemental metal atoms due to its unique
4d$^{10}$5s$^0$ configuration. Relativistic effects are found to be already
sizeable ($\Delta_R\alpha$= +1.86~a.u.) compared to electron correlation
($\Delta_C\alpha$= +5.06~a.u.), and need to be included for the accurate
determination of the dipole polarizability. We also report a value of the
second hyperpolarizability to be $\gamma\approx$ 40,000~a.u., but here the
coupled-cluster contributions are not yet converged out with respect to higher
than quintuple excitations.
