CREATE TABLE table_28317 ("City / Municipality" TEXT, "Date of Creation" TEXT, "Area  ( km 2  ) " TEXT, "Population  ( 2010 ) " FLOAT, "Income Classification  (  DOF  ) " TEXT)

How many city/municipalties have an area (km2) of 506.64?
SELECT COUNT("City / Municipality") FROM table_28317 WHERE "Area (km 2 )" = '506.64'
SELECT COUNT("City / Municipality") FROM "table_28317" WHERE "Area (km 2 )" = '506.64'