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_21146729_6 ( series__number INTEGER, original_airdate VARCHAR )

### Question ###
What was the series# with the original airdate of october 23, 1967?

### Accurate SQL ###

SELECT MAX(series__number) FROM table_21146729_6 WHERE original_airdate = "October 23, 1967"