I'm not sure how you compute the density of agcl using the length of a unit cell edge measure of 555 pm.
But as per online research, the density of AgCl is 5.56 g/cm³
AgCl is the chemical formula of silver chloride. It<span> is easily synthesized by combining aqueous solutions of silver nitrate and sodium chloride. </span> AgNO₃ + NaCl → AgCl↓ + NaNO₃
