How many city/municipalties have an area (km2) of 506.64?
CREATE TABLE table_28317 (
    "City / Municipality" text,
    "Date of Creation" text,
    "Area (km 2 )" text,
    "Population (2010)" real,
    "Income Classification ( DOF )" text
)
SELECT COUNT("City / Municipality") FROM table_28317 WHERE "Area (km 2 )" = '506.64'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many city/municipalties have an area (km2) of 506.64? ### Input: CREATE TABLE table_28317 (
    "City / Municipality" text,
    "Date of Creation" text,
    "Area (km 2 )" text,
    "Population (2010)" real,
    "Income Classification ( DOF )" text
) ### Response: SELECT COUNT("City / Municipality") FROM table_28317 WHERE "Area (km 2 )" = '506.64'