110 ( 73 + 37 )

Sheldon Cooper feels that 73 is the best number:

"73 is the 21st prime number. Its mirror 37 is the 12th prime number."

But what he says about 73 is also true about 37.
"73 is the 21st prime number. Its mirror 37 is the 12th prime number" can also be put as
"37 is the 12st prime number. Its mirror 73 is the 21th prime number".

(This is listed under 110 because the real beauty is  37 and 73 together.)

OK, 73 is a palindrome in binary (1001001) and 37 isn't (100101).

but they are both palindromes in morse code:  
37 is     . . .  - -    - -  . . .      while 73 is  - - . . .    . . . - -