What is the 643rd prime number?
The 643rd prime number is 4787. The next prime is 4789 (a gap of 2) and the one before is 4783.
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 643rd one is 4787.
- 2
4787 is prime because no prime up to ā4787 ā 69.19 divides it.
- 3
The primes are spread thinner as numbers grow: by the prime number theorem the 643rd prime is close to 643 Ć ln(643) ā 4158, and here it is 4787.
- 4
4787 is a twin prime: 4787 and 4789 are both prime.
Primes around the 643rd
| Position | Prime | Gap from the previous |
|---|---|---|
| 640 | 4751 | 18 |
| 641 | 4759 | 8 |
| 642 | 4783 | 24 |
| 643 | 4787 | 4 |
| 644 | 4789 | 2 |
| 645 | 4793 | 4 |
| 646 | 4799 | 6 |
Questions
What is the 643rd prime number?
4787.
Which prime number is 4787?
4787 is the 643rd prime number.
What is the sum of the first 643 primes?
1,420,724.