The atomic number of Indium is 49. Indium is a chemical element in the periodic table that has the symbol In and atomic number 49. It is a post-transition metal that is rare in Earth's crust. Indium has a melting point of 156.6 °C and a boiling point of 2072 °C. It is a soft, malleable, and ductile metal with a bright silvery luster. Indium is used in semiconductors, electronics, and alloys.