What is the 18th prime number?
The 18th prime number is 61. The next prime is 67 (a gap of 6) and the one before is 59.
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 18th one is 61.
- 2
61 is prime because no prime up to ā61 ā 7.81 divides it.
- 3
The primes are spread thinner as numbers grow: by the prime number theorem the 18th prime is close to 18 Ć ln(18) ā 52, and here it is 61.
- 4
61 is a twin prime: 59 and 61 are both prime.
Primes around the 18th
| Position | Prime | Gap from the previous |
|---|---|---|
| 15 | 47 | 4 |
| 16 | 53 | 6 |
| 17 | 59 | 6 |
| 18 | 61 | 2 |
| 19 | 67 | 6 |
| 20 | 71 | 4 |
| 21 | 73 | 2 |
Questions
What is the 18th prime number?
61.
Which prime number is 61?
61 is the 18th prime number.
What is the sum of the first 18 primes?
501.