What is the 43rd prime number?
The 43rd prime number is 191. The next prime is 193 (a gap of 2) and the one before is 181.
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 43rd one is 191.
- 2
191 is prime because no prime up to ā191 ā 13.82 divides it.
- 3
The primes are spread thinner as numbers grow: by the prime number theorem the 43rd prime is close to 43 Ć ln(43) ā 162, and here it is 191.
- 4
191 is a twin prime: 191 and 193 are both prime.
Primes around the 43rd
| Position | Prime | Gap from the previous |
|---|---|---|
| 40 | 173 | 6 |
| 41 | 179 | 6 |
| 42 | 181 | 2 |
| 43 | 191 | 10 |
| 44 | 193 | 2 |
| 45 | 197 | 4 |
| 46 | 199 | 2 |
Questions
What is the 43rd prime number?
191.
Which prime number is 191?
191 is the 43rd prime number.
What is the sum of the first 43 primes?
3,638.