What is the 243rd prime number?
The 243rd prime number is 1543. The next prime is 1549 (a gap of 6) and the one before is 1531.
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 243rd one is 1543.
- 2
1543 is prime because no prime up to ā1543 ā 39.28 divides it.
- 3
The primes are spread thinner as numbers grow: by the prime number theorem the 243rd prime is close to 243 Ć ln(243) ā 1335, and here it is 1543.
- 4
1543 has no twin: neither 1541 nor 1545 is prime.
Primes around the 243rd
| Position | Prime | Gap from the previous |
|---|---|---|
| 240 | 1511 | 12 |
| 241 | 1523 | 12 |
| 242 | 1531 | 8 |
| 243 | 1543 | 12 |
| 244 | 1549 | 6 |
| 245 | 1553 | 4 |
| 246 | 1559 | 6 |
Questions
What is the 243rd prime number?
1543.
Which prime number is 1543?
1543 is the 243rd prime number.
What is the sum of the first 243 primes?
171,148.