Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_21146729_6 (series__number VARCHAR, original_airdate VARCHAR)
### Question:
How  many of the  series # when the original airdate is september 25, 1967?
### Answer:
SELECT COUNT(series__number) FROM table_21146729_6 WHERE original_airdate = "September 25, 1967"