Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_221398_1 ( pop_density___km²_ VARCHAR, number_in_map VARCHAR )

### Question ###
How many prefectures have a population density of 16 people/kilometers squared?

### Accurate SQL ###

SELECT COUNT(pop_density___km²_) FROM table_221398_1 WHERE number_in_map = "16"