A swag of new data released on Tuesday from the latest census shows for the first time the Baby Boomer proportion of the population and the Millennial proportion are equal.

Both demographic groups comprise 5.4 million people, but the 2021 statistics suggest that since the 2016 survey, boomer numbers are diminishing.

The national population as of 2021 grew by about two million people to 25.4 million since the last census.

The census took place in August 2021 during the height of COVID-19 restrictions and lockdowns.

Since the last census, almost one million new private dwellings were added, with more than 11 million counted across the country.

Of those, 70 per cent were separate homes, 16 per cent were apartments and 13 per cent were townhouses, while the proportion of apartments continues to increase.

More than eight million Australians are living with long-term health conditions, two million of whom suffer mental health, arthritis or asthma.

Women are more likely to report having a long-term health condition, with 34 per cent suffering at least one, compared to 30 per cent of men.

Mental health was one of the most commonly reported conditions across both genders, while females commonly reported arthritis and men reported asthma.

Australians under the age of 14 were the most likely to have asthma.

More than 4.8 million people said they suffered one of the 10 long-term conditions listed in the census, 1.5 million reported living with two, and 750,000 have three.

Australia has more than a million single-parent families with four out of five parents female.

Nearly 24,000 same-sex marriages have been recorded since laws changed in 2017. It equals 0.25 per cent of all unions.

Divorces continue to increase, with 1.8 million Australians aged more than 15 years divorced, up from 1.4 million in 2011 and 1.6 million in 2016.

people aged over 55 years looking after another person's child had risen by 140,000 people at the 2016 Census, but then dropped by 50,000 at the 2021 count.

Census data revealed on Tuesday that there are 812,728 people who identify as Aboriginal or Torres Strait Islander in Australia. That's equal to 3.2 per cent of the population.

The figures reflect an increase of more than 25 per cent since census data was last collected in 2016.

Nearly 48,000 are aged 65 years and older which more than doubles the results of the 2011 census.

Traditional languages remain an important part of many Indigenous households. More than 78,000 people speak an Aboriginal or Torres Strait Islander language at home.

Christianity remains Australia's most common religion, but the number of followers continues to decline, according to new statistics.

The 2021 census revealed on Tuesday that 43.9 per cent of Australians identify as Christian, with Catholic being the largest denomination . In 2016 that number was 52.1 per cent and in 2011 it was 61.1 per cent.

Some other religions are growing. Hinduism was listed by 2.7 per cent of census respondents and Islam grew to 3.2 per cent.

An increasing number of people are also reporting they are not religious, with the 2021 census showing 38.9 per cent have no religious affiliation.

- with AAP