CREATE TABLE table_73638 ("Episode number Production number" TEXT, "Title" TEXT, "Original airdate" TEXT, "Rating/Share in Households" TEXT, "18\\u201349 Rating Live+SD / Live+7" TEXT, "Share" TEXT, "Live+SD Total viewers" TEXT, "Live+7 Day DVR Total viewers" TEXT)

When did the episode that had 3.69 million total viewers (Live and SD types combined) first air?
SELECT "Original airdate" FROM table_73638 WHERE "Live+SD Total viewers" = '3.69 million'
SELECT "Original airdate" FROM "table_73638" WHERE "Live+SD Total viewers" = '3.69 million'