According to the map below, there are approximately 150 to 299 people per square kilometer in the country of India.
India has a land area of 3.286 million square kilometer.
So there can be around 492.9 million to 982.514 million people living in India.
3.286 million square km * 150 / sq. km = 492.9 million
3.286 million square km * 299 / sq. km = 982.514 million