Compare 1 vs 2
| Property | 1 | 2 |
|---|---|---|
| Type | composite number | prime |
| Unique factors | 0 | 1 |
| Total factors | 0 | 1 |
| Prime factorization | 21 | |
| Prime factorization | 2 | |
| Divisors count | 1 | 2 |
| Divisors | 1 | 1, 2 |
| Number of properties | 0 | 26 |
| Additive primes | 1st | |
| Bell primes | 1st | |
| Chen primes | 1st | |
| Class 1+ primes | 1st | |
| Dihedral primes | 1st | |
| Euclid primes | 1st | |
| Factorial primes | 1st | |
| Fibonacci primes | 1st | |
| Isolated primes | 1st | |
| Kynea primes | 1st | |
| Left-truncatable primes | 1st | |
| Lucas primes | 1st | |
| Mills primes | 1st | |
| Multiplicative primes | 1st | |
| Palindromic primes | 1st | |
| Pierpont primes | 1st | |
| Pierpont primes of the 2nd kind | 1st | |
| Primes | 1st | |
| Quartan primes | 1st | |
| Restricted left-truncatable primes | 1st | |
| Right-truncatable primes | 1st | |
| Sophie germain primes | 1st | |
| Thabit primes | 1st | |
| Two-sided primes | 1st | |
| Ulam primes | 1st | |
| Wedderburn-etherington primes | 1st | |
| Roman numberals | I | II |
| Base 2 | 12 | 102 |
| Base 3 | 13 | 23 |
| Base 4 | 14 | 24 |
| Base 5 | 15 | 25 |
| Base 6 | 16 | 26 |
| Base 7 | 17 | 27 |
| Base 8 | 18 | 28 |
| Base 9 | 19 | 29 |
| Base 10 | 110 | 210 |
| Base 11 | 111 | 211 |
| Base 12 | 112 | 212 |
| Base 13 | 113 | 213 |
| Base 14 | 114 | 214 |
| Base 15 | 115 | 215 |
| Base 16 | 116 | 216 |