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_21109892_1 (quantity_world_rank VARCHAR, value_world_rank VARCHAR)

### Question ###
where value world rank is 12, what is the quantity world rank?

### Accurate SQL ###

SELECT quantity_world_rank FROM table_21109892_1 WHERE value_world_rank = "12"