The number 689
689 is a composite number with 4 divisors. Its prime factorisation is 13 × 53. Divisors (4): 1, 13, 53, 689.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 689: a semiprime: 13 × 53, the product of two primes.
- 2
689 is composite. Its prime factorisation is
- 3
The divisors add up to 756; without 689 itself that is 67, so 689 is deficient (67 is less than 689). Euler's totient φ(689) = 624 numbers up to 689 share no factor with it.
- 4
The digits of 689 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 126 steps to reach 1.
LaTeX source of the formulas on this page
\[ 689 = 13 \times 53 \]
689 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 756 |
| Euler totient φ(n) | 624 |
| Square | 474721 |
| Cube | 327082769 |
| Square root | 26.248809 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 126 |
| Scientific notation | 6.89 × |
689 in other forms
| Form | Value |
|---|---|
| In words | six hundred and eighty-nine |
| Roman numerals | DCLXXXIX |
| Binary (base 2) | 1010110001 |
| Octal (base 8) | 1261 |
| Hexadecimal (base 16) | 2B1 |
| Base 3 | 221112 |
| As time | 689 seconds = 11 min 29 s |
Is 689 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 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 5) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 689 a prime number?
No. 689 = 13 × 53, so it is divisible by 13.
What are the factors of 689?
1, 13, 53, 689.
What is 689 in binary?
1010110001 (hexadecimal 2B1, octal 1261).
What is the square root of 689?
About 26.2488.
What is 689 in Roman numerals?
DCLXXXIX.
Is 689 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 689?
689 is a semiprime: 13 × 53, the product of two primes.