The number 13581
13581 is a composite number with 8 divisors. Its prime factorisation is × 503. Divisors (8): 1, 3, 9, 27, 503, 1509, 4527, 13581.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 13581: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
13581 is composite. Its prime factorisation is
- 3
The divisors add up to 20160; without 13581 itself that is 6579, so 13581 is deficient (6579 is less than 13581). Euler's totient φ(13581) = 9036 numbers up to 13581 share no factor with it.
- 4
The digits of 13581 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 37 steps to reach 1.
LaTeX source of the formulas on this page
\[ 13581 = 3^{3} \times 503 \]13581 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 20160 |
| Euler totient φ(n) | 9036 |
| Square | 184443561 |
| Cube | 2504928001941 |
| Square root | 116.537548 (= 3√1509) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 37 |
| Scientific notation | 1.3581 × |
13581 in other forms
| Form | Value |
|---|---|
| In words | thirteen thousand five hundred and eighty-one |
| Binary (base 2) | 11010100001101 |
| Octal (base 8) | 32415 |
| Hexadecimal (base 16) | 350D |
| Base 3 | 200122000 |
| As time | 13581 seconds = 3 h 46 min 21 s |
Is 13581 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 (13581 ÷ 3 = 4527) | 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (13581 ÷ 9 = 1509) | 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 7) | 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 13581 a prime number?
No. 13581 = × 503, so it is divisible by 3.
What are the factors of 13581?
1, 3, 9, 27, 503, 1509, 4527, 13581.
What is 13581 in binary?
11010100001101 (hexadecimal 350D, octal 32415).
What is the square root of 13581?
About 116.5375, exactly 3√1509.
Is 13581 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 13581?
13581 is a happy number: repeatedly adding the squares of its digits reaches 1.