Compare 21987 vs 21991
| Property | 21987 | 21991 |
|---|---|---|
| Type | composite number | prime |
| Unique factors | 3 | 1 |
| Total factors | 4 | 1 |
| Prime factorization | 32 × 71 × 3491 | 219911 |
| Prime factorization | 3 × 3 × 7 × 349 | 21991 |
| Divisors count | 12 | 2 |
| Divisors | 1, 3, 7, 9, 21, 63, 349, 1047, 2443, 3141, 7329, 21987 | 1, 21991 |
| Number of properties | 0 | 5 |
| Chen primes | 1208th | |
| Isolated primes | 1720th | |
| Primes | 2463rd | |
| Sexy primes (1st member) | 742nd | |
| Sexy prime triplets (1st member) | 202nd | |
| Roman numberals | ||
| Base 2 | 1010101111000112 | 1010101111001112 |
| Base 3 | 10100111003 | 10100111113 |
| Base 4 | 111132034 | 111132134 |
| Base 5 | 12004225 | 12004315 |
| Base 6 | 2454436 | 2454516 |
| Base 7 | 1210507 | 1210547 |
| Base 8 | 527438 | 527478 |
| Base 9 | 331409 | 331449 |
| Base 10 | 2198710 | 2199110 |
| Base 11 | 1557911 | 1558211 |
| Base 12 | 1088312 | 1088712 |
| Base 13 | a01413 | a01813 |
| Base 14 | 802714 | 802b14 |
| Base 15 | 67ac15 | 67b115 |
| Base 16 | 55e316 | 55e716 |