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_13836704_6 ( rank VARCHAR, freight___metric_tonnes__ VARCHAR )

### Question ###
What is the rank of the airport with a freight ( metric tonnes ) of 23791?

### Accurate SQL ###

SELECT rank FROM table_13836704_6 WHERE freight___metric_tonnes__ = 23791