What is the 391st prime number?
The 391st prime number is 2689. The next prime is 2693 (a gap of 4) and the one before is 2687.
Position
Pick any whole number from 1 to 10,000.
How to work it out
- 1
List the primes in order: 2, 3, 5, 7, 11, 13, ā¦ The 391st one is 2689.
- 2
2689 is prime because no prime up to ā2689 ā 51.86 divides it.
- 3
The primes are spread thinner as numbers grow: by the prime number theorem the 391st prime is close to 391 Ć ln(391) ā 2334, and here it is 2689.
- 4
2689 is a twin prime: 2687 and 2689 are both prime.
Primes around the 391st
| Position | Prime | Gap from the previous |
|---|---|---|
| 388 | 2677 | 6 |
| 389 | 2683 | 6 |
| 390 | 2687 | 4 |
| 391 | 2689 | 2 |
| 392 | 2693 | 4 |
| 393 | 2699 | 6 |
| 394 | 2707 | 8 |
Questions
What is the 391st prime number?
2689.
Which prime number is 2689?
2689 is the 391st prime number.
What is the sum of the first 391 primes?
483,382.