The number 73 is the 21st prime number, and its reverse 37 is the 12th prime, while 21 is the product of 7 and 3—making it a 'prime factor mirror prime' and Sheldon Cooper's favorite number in The Big Bang Theory.
Sources
- https://en.wikipedia.org/wiki/73_(number) (en.wikipedia.org)
- https://en.wikipedia.org/wiki/37_(number) (en.wikipedia.org)
- https://www.mathnasium.com/math-centers/westcounty/news/bang-math-professors-prove-tv-show-theory-about-the-number-73 (mathnasium.com)
- https://prime-numbers.fandom.com/wiki/73 (prime-numbers.fandom.com)
- https://www.r-bloggers.com/2024/10/sheldon-coopers-favorite-number/ (r-bloggers.com)
- https://www.wusa9.com/article/entertainment/television/cbs-shows/best-of-big-bang-theory-why-73-is-the-chuck-norris-of-numbers/65-4219879f-8708-4aa1-8949-22b796e1b531 (wusa9.com)
- https://www.geeksforgeeks.org/maths/is-73-a-prime-number/ (geeksforgeeks.org)
- https://www.filmgarb.com/sheldons-73-shirt/ (filmgarb.com)
- https://prime-numbers.info/number/12th-prime (prime-numbers.info)
- https://argoprep.online/blog/is-37-a-prime-number/ (argoprep.online)