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_23287683_1 (season__number VARCHAR, production_code VARCHAR)
### Question:
List all season numbers with production codes of 5m21.
### Answer:
SELECT season__number FROM table_23287683_1 WHERE production_code = "5M21"