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_23151 ( "LGA Name" text, "Area (km 2 )" real, "Census 2006 population" real, "Administrative capital" text, "Postal Code" real )

### Question ###
How many areas (km 2) have 151511 as the census 2006 population?

### Accurate SQL ###

SELECT COUNT("Area (km 2 )") FROM table_23151 WHERE "Census 2006 population" = '151511'