CI 77891 (Titanium Dioxide) is a white pigment used in cosmetics and personal care products to achieve a rich opaque color in formulations. It can further be mixed with other dyes to achieve different hues and shades in a product. In addition to this, CI 77891 is also beneficial in blocking potentially harmful UV rays and is therefore widely used in sunscreens. The chemical formula for titanium dioxide is TiO2. A similar ingredient to CI 77891 is zinc oxide, which is also a white dye and has a slightly better performance in protecting against the sun's rays than titanium dioxide. https://cosmetics.specialchem.com/inci-ingredients/ci-77891