What was the population density in km2 for 2011 in the division where area in km2 was 684.37 in 2011?
create table table_24027047_1 (population_density___km²_2011_ varchar, area__km²__2011 varchar, PRIMARY KEY (population_density___km²_2011_))
select population_density___km²_2011_ from table_24027047_1 where area__km²__2011 * * = "684.37"