| Next prime | 43 |
| Previous prime | 37 |
| Octal | (51)8 |
| Hexadecimal | (29)16 |
| Prime gap | 2 |
| 6th Twin prime (the small number) | The big number is 43 . |
| 7th Prime triplet (the smallest number) | The others are 43 and 47 . |
| 9th Sexy prime (the small number) | The big number is 47 . |
| 6th Prime of the Form 4n+1 | 42 + 52 |
| 1st Euler prime number | |
| 7th Sophie Germain prime |