The number 681
681 is a composite number with 4 divisors. Its prime factorisation is 3 × 227. Divisors (4): 1, 3, 227, 681.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 681: a semiprime: 3 × 227, the product of two primes.
- 2
681 is composite. Its prime factorisation is
- 3
The divisors add up to 912; without 681 itself that is 231, so 681 is deficient (231 is less than 681). Euler's totient φ(681) = 452 numbers up to 681 share no factor with it.
- 4
The digits of 681 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 64 steps to reach 1.
LaTeX source of the formulas on this page
\[ 681 = 3 \times 227 \]
681 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 912 |
| Euler totient φ(n) | 452 |
| Square | 463761 |
| Cube | 315821241 |
| Square root | 26.095977 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 64 |
| Scientific notation | 6.81 × |
681 in other forms
| Form | Value |
|---|---|
| In words | six hundred and eighty-one |
| Roman numerals | DCLXXXI |
| Binary (base 2) | 1010101001 |
| Octal (base 8) | 1251 |
| Hexadecimal (base 16) | 2A9 |
| Base 3 | 221020 |
| As time | 681 seconds = 11 min 21 s |
Is 681 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 | Yes (681 ÷ 3 = 227) | 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 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 681 a prime number?
No. 681 = 3 × 227, so it is divisible by 3.
What are the factors of 681?
1, 3, 227, 681.
What is 681 in binary?
1010101001 (hexadecimal 2A9, octal 1251).
What is the square root of 681?
About 26.0960.
What is 681 in Roman numerals?
DCLXXXI.
Is 681 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 681?
681 is a semiprime: 3 × 227, the product of two primes.