Well, I did remember "two little ducks" and didn't remember "the Lord is my shepherd", but that might just mean my interests are more ornithological than ecclesiastical. 23 is the smallest prime number that's not two away from another prime number. It's the number of chromosomes we typically have. 23 is the number of people you need to have before it's likely that at least two share a birthday. It's the lane number that the protagonists used in the Big Lebowski. 22 is relatively boring - it's just twice a prime. The best way I've got to remember it is Catch 22. Does that help? Down with 22, up with 23.