Seventy Three

"The best number is 73. Why? 73 is the 21st prime number. Its mirror (37) is the 12th and its mirror (21) is the product of multiplying, hang on to your hats, 7 and 3. ... In binary, 73 is a palindrome, 1,0,0,1,0,0,1 which backwards is 1,0,0,1,0,0,1." - Dr Sheldon Cooper
See Also: http://en.wikipedia.org/wiki/73_%28number%29

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