There were 49 towns in the country with a population of more than 10,000, with over two-thirds of them in Leinster.
The CSO has released more statistics from the Census conducted last April.
Drogheda in Louth was found to be the largest town last year with a population of more than 44,000.
The Census also found that of those large towns the one with the oldest average age is Clonmel in Tipperary - while the youngest is Balbriggan in north county Dublin.
While in smaller towns with a population of 1,500 to 10,000 the youngest average age was Saggart in west Dublin.
The CSO found the oldest small towns were both Ballyshannon in Donegal and Dingle-Daingean Úi Chuis i gcontae Ciarraí.
It also looked at whether people stayed in the county they were born and Cork had the highest percentage of people not moving out at 72 percent.
However, Meath had the lowest percentage of residents who were born there.
Between 2016 and 2022 more than 265,000 people moved home within Ireland and more than a quarter of them moved county.