The number 581
581 is a composite number with 4 divisors. Its prime factorisation is 7 × 83. Divisors (4): 1, 7, 83, 581.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 581: a semiprime: 7 × 83, the product of two primes.
- 2
581 is composite. Its prime factorisation is
- 3
The divisors add up to 672; without 581 itself that is 91, so 581 is deficient (91 is less than 581). Euler's totient φ(581) = 492 numbers up to 581 share no factor with it.
- 4
The digits of 581 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 118 steps to reach 1.
LaTeX source of the formulas on this page
\[ 581 = 7 \times 83 \]
581 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 672 |
| Euler totient φ(n) | 492 |
| Square | 337561 |
| Cube | 196122941 |
| Square root | 24.103942 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 118 |
| Scientific notation | 5.81 × |
581 in other forms
| Form | Value |
|---|---|
| In words | five hundred and eighty-one |
| Roman numerals | DLXXXI |
| Binary (base 2) | 1001000101 |
| Octal (base 8) | 1105 |
| Hexadecimal (base 16) | 245 |
| Base 3 | 210112 |
| As time | 581 seconds = 9 min 41 s |
Is 581 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 1) | 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 | Yes (581 ÷ 7 = 83) | 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 5) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 581 a prime number?
No. 581 = 7 × 83, so it is divisible by 7.
What are the factors of 581?
1, 7, 83, 581.
What is 581 in binary?
1001000101 (hexadecimal 245, octal 1105).
What is the square root of 581?
About 24.1039.
What is 581 in Roman numerals?
DLXXXI.
Is 581 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 581?
581 is a semiprime: 7 × 83, the product of two primes.