Sheldon: What is the best number? By the way, there's only one correct answer. Raj: 5,318,008? Sheldon: Wrong! The best number is 73. [Short silence] You're probably wondering why. Leonard & Howard: No no, we're good. Sheldon: 73, is the 21st prime number, it's mirror 37 is the 12th and it's mirror 21 is the product of multiplying, hang on to your hats, 7 and 3. Did I lie? Leonard: We did it! 73 is the... Chuck Norris of numbers! Sheldon: Chuck Norris wishes! In binary, 73 is a palindrome, 1001001, which backwards is 1001001, exactly the same. All Chuck Norris gets you backwards is Sirron Kcuhc! Raj: Just for the record, when you enter 5,318,008 in a calculator, upside down it spells BOOBIES!