India has a diverse population of a billion-plus people
More people now live in India than in the United States, Indonesia, Brazil, Pakistan and Bangladesh combined.
Although its rate of population growth is slowing, India is on course to overtake China as the most populous country around 2030, figures show.
The census also reveals a continuing preference for boys - India's sex ratio is at its worst since independence.
Statistics for the past 10 years show fewer girls than boys are being born or surviving. They show 914 girls were born for every 1,000 boys under the age of six, compared with 927 for every 1,000 in 2001 census.
"This is a matter of grave concern," Census Commissioner C Chandramauli told a press conference in the capital, Delhi.
The population of India now comprises 623.7 million males and 586.5 million females.
Mr Chandramauli said the increase in the population over the past decade tallies with official estimates.
The data shows India's massive population growing fast - 181 million is roughly equivalent to the entire population of Brazil - but the rate of growth has slowed.
The 2011 census charts a population increase of 17.6% from 2001, compared with one of 21.5 in the previous decade.
Uttar Pradesh remains India's most populous state - 199 million people now live there.
In the field of education there was good news, with the census showing the literacy rate going up to 74% from about 65% in the last count.
India launched the 2011 census last year. The exercise costs in the region of 22bn rupees ($490m; £300m).
Some 2.7 million officials visited households in about 7,000 towns and 600,000 villages, classifying the population according to gender, religion, education and occupation.
The exercise, conducted every 10 years, faces big challenges, not least India's vast area and diversity of cultures.
Census officials also have to contend with high levels of illiteracy and millions of homeless people - as well as insurgencies by Maoists and other rebels which have left large parts of the country unsafe.