CREATE TABLE table_21164557_1 (original_air_date VARCHAR2, production_code VARCHAR2)

How many original air dates were there for episodes with a production code of 4398016?
SELECT COUNT(original_air_date) FROM table_21164557_1 WHERE production_code = 4398016
SELECT COUNT("original_air_date") FROM "table_21164557_1" WHERE "production_code" = 4398016