The number 2689
2689 is a twin prime (2687 and 2689 are both prime) and the 391st prime number. Its only divisors are 1 and 2689.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 2689: a twin prime (2687 and 2689 are both prime); the 391st prime number.
- 2
2689 is prime, so its only factors are 1 and 2689. It is the 391st prime; the next prime is 2693 and the one before is 2687.
- 3
The divisors add up to 2690; without 2689 itself that is 1, so 2689 is deficient (1 is less than 2689). Euler's totient φ(2689) = 2688 numbers up to 2689 share no factor with it.
- 4
The digits of 2689 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 71 steps to reach 1.
2689 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 2690 |
| Euler totient φ(n) | 2688 |
| Square | 7230721 |
| Cube | 19443408769 |
| Square root | 51.855569 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 71 |
| Scientific notation | 2.689 × |
2689 in other forms
| Form | Value |
|---|---|
| In words | two thousand six hundred and eighty-nine |
| Roman numerals | MMDCLXXXIX |
| Binary (base 2) | 101010000001 |
| Octal (base 8) | 5201 |
| Hexadecimal (base 16) | A81 |
| Base 3 | 10200121 |
| As time | 2689 seconds = 44 min 49 s |
Is 2689 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 2689 a prime number?
Yes. 2689 is divisible only by 1 and itself.
What are the factors of 2689?
1, 2689.
What is 2689 in binary?
101010000001 (hexadecimal A81, octal 5201).
What is the square root of 2689?
About 51.8556.
What is 2689 in Roman numerals?
MMDCLXXXIX.
Is 2689 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 2689?
2689 is a twin prime (2687 and 2689 are both prime); the 391st prime number.