For $\ce{HgCl2}$ ($M = \pu{271.52 g mol-1}$), the reported $K_\mathrm{sp}$ value is $10^{-15.69}$.
This means that the calculated molar solubility of $\ce{HgCl2}$ in water is $(10^{-15.69}/4)^{1/3}\cdot\pu{271.52 g mol-1} \approx \pu{0.0010 g L-1}$, or equivalently, $\pu{0.010 g cm-3}$.
However, in Pubchem, the reported molar solubility is 6.9 g/100 cc. What is the source of the large deviation between the experimental and the theoretically calculated molar solubility of $\ce{HgCl2}$?