73 (the 21st prime)

 
Next prime79
Previous prime71
Octal(111)8
Hexadecimal(49)16
Prime gap6
14th Sexy prime (the small number)The big number is 79 .
9th Prime of the Form 3n+152 + 3 * 42
9th Prime of the Form 4n+132 + 82
6th Emirp (reversible prime) 
13th Left-truncatable prime 
12th Right-truncatable prime 
8th Two-sided prime