text: 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_22170495_6 (total_viewers VARCHAR, original_airing_on_channel_4 VARCHAR)
  ### Question:
  How many total viewers have April 21, 2010 as the original airing on channel 4?
  ### Answer:
  SELECT COUNT(total_viewers) FROM table_22170495_6 WHERE original_airing_on_channel_4 = "April 21, 2010"