Let's recall some basic information (as per latest data)

State with maximum population - Uttar pradesh

State with least population - Sikkim

State with highest density - Bihar

State with lowest density - Arunachal pradesh
(Density refers to no. Of population in per square km of area)

Population of India - 1.38 billion (138crore)

World rank in population - 2nd ,just after China

Percentage of world population - 17.71%