Sheldon number.
In the series The Big Bang theory, Sheldon's favorite number is 73
Because (
in base 10), this number has certain property.
1. 73 is prime
2. It's reverse: 37 is also prime.
3. 73 is the 21st prime.
4. 37 is the 12th prime.
5. It's digit product 7 * 3 is also 21 (see property 3)
So, does 73 (in base 10) is the only number who have this property?
What about other number in base 10?
What about other number in any other base?
Here, I try to find any prime numbers in any other base who have this property. But, I can only find 73 in base 10.
I've searched up until base 2000. Larger than this, it would take more programming effort to conserve memories and speed up process. I just write this software in 1 hour. Perhaps any mathematicians here can prove that only 73 and in base 10 number that has this property. That there's no other possibilty in any other base. Just like 1089 problem above.
This 1089 works in any base number.