Compare 21991 vs 21998
| Property | 21991 | 21998 |
|---|---|---|
| Type | prime | composite number |
| Unique factors | 1 | 3 |
| Total factors | 1 | 3 |
| Prime factorization | 219911 | 21 × 171 × 6471 |
| Prime factorization | 21991 | 2 × 17 × 647 |
| Divisors count | 2 | 8 |
| Divisors | 1, 21991 | 1, 2, 17, 34, 647, 1294, 10999, 21998 |
| Number of properties | 5 | 0 |
| Chen primes | 1208th | |
| Isolated primes | 1720th | |
| Primes | 2463rd | |
| Sexy primes (1st member) | 742nd | |
| Sexy prime triplets (1st member) | 202nd | |
| Roman numberals | ||
| Base 2 | 1010101111001112 | 1010101111011102 |
| Base 3 | 10100111113 | 10100112023 |
| Base 4 | 111132134 | 111132324 |
| Base 5 | 12004315 | 12004435 |
| Base 6 | 2454516 | 2455026 |
| Base 7 | 1210547 | 1210647 |
| Base 8 | 527478 | 527568 |
| Base 9 | 331449 | 331529 |
| Base 10 | 2199110 | 2199810 |
| Base 11 | 1558211 | 1558911 |
| Base 12 | 1088712 | 1089212 |
| Base 13 | a01813 | a02213 |
| Base 14 | 802b14 | 803414 |
| Base 15 | 67b115 | 67b815 |
| Base 16 | 55e716 | 55ee16 |