Of the 11 districts in Delhi spread over 1,483 sq km, the northeastern part of the city has the highest number of dwellers, the census said.

Delhi is followed by Chandigarh with 9,252 people per sq km.

The least densely populated state in the country is Arunachal Pradesh with 17 people per sq km, followed by the union territory of Andaman and Nicobar Islands with 46 people per square km.

Dibang Valley in Arunachal Pradesh is the least densely populated district in the country with one person per square kilometre, followed by Samba district in Jammu and Kashmir with two people per square kilometre.

With 26,903 people per square km, Chennai is the most densely populated district.

An estimated 2.7 million officials had fanned out across the country to undertake Census 2011 which was conducted in two phases -- houselisting and housing census and then population enumeration, costing the government Rs.22,000 million.

The decadal exercise -- the 15th headcount of India's population since 1872 -- is undertaken to create a database on demography, economic activity, literacy and education, housing and household amenities, urbanisation, fertility and mortality, social structure, language, religion and migration.