Electronic Devices: JEE Main 2021 Physics question

In a semiconductor, the number density of intrinsic charge carries at 27$^\circ$C is 1.5 $\times$ 10¹⁶/m³. If the semiconductor is doped with impurity atom, the hole density increases to 4.5 $\times$ 10²²/m³. The electron density in the doped semiconductor is ___________ $\times$ 10⁹/m³.