Watch how "73 is the Best Number" (According to Sheldon, Simplified): It’s a prime number That means it can only be divided by 1 and itself. So, 73 is a prime. Its mirror is also a prime Flip 73 and you get 37 — that’s also a prime number! Their positions are reversed too! 73 is the 21st prime number. 37 is the 12th prime number. 21 and 12 — mirror numbers again! In binary, it gets even cooler 73 in binary is 1001001 That’s a palindrome — it reads the same forward and backward. So in short: It's

What are Prime Numbers 1 to 100? Definition, Chart, Examples