What is the population density of the administrative division with a population in 2010 of 264170 according to the census?
create table table_21734764_1 (population_density___km²_2010_ varchar, population_2010_census varchar, PRIMARY KEY (population_density___km²_2010_))
select population_density___km²_2010_ from table_21734764_1 where population_2010_census = 264170