Compare 2 vs 21
Property | 2 | 21 |
---|---|---|
Type | prime | semiprime |
Unique factors | 1 | 2 |
Total factors | 1 | 2 |
Prime factorization | 21 | 31 × 71 |
Prime factorization | 2 | 3 × 7 |
Divisors count | 2 | 4 |
Divisors | 1, 2 | 1, 3, 7, 21 |
Number of properties | 26 | 1 |
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 | |
Semiprimes | 7th | |
Sophie germain primes | 1st | |
Thabit primes | 1st | |
Two-sided primes | 1st | |
Ulam primes | 1st | |
Wedderburn-etherington primes | 1st | |
Roman numberals | II | XXI |
Base 2 | 102 | 101012 |
Base 3 | 23 | 2103 |
Base 4 | 24 | 1114 |
Base 5 | 25 | 415 |
Base 6 | 26 | 336 |
Base 7 | 27 | 307 |
Base 8 | 28 | 258 |
Base 9 | 29 | 239 |
Base 10 | 210 | 2110 |
Base 11 | 211 | 1a11 |
Base 12 | 212 | 1912 |
Base 13 | 213 | 1813 |
Base 14 | 214 | 1714 |
Base 15 | 215 | 1615 |
Base 16 | 216 | 1516 |