The number 81513
81513 is a composite number with 8 divisors. Its prime factorisation is × 3019. Divisors (8): 1, 3, 9, 27, 3019, 9057, 27171, 81513.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81513: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81513 is composite. Its prime factorisation is
- 3
The divisors add up to 120800; without 81513 itself that is 39287, so 81513 is deficient (39287 is less than 81513). Euler's totient φ(81513) = 54324 numbers up to 81513 share no factor with it.
- 4
The digits of 81513 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 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81513 = 3^{3} \times 3019 \]81513 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 120800 |
| Euler totient φ(n) | 54324 |
| Square | 6644369169 |
| Cube | 541602464072697 |
| Square root | 285.504816 (= 3√9057) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.1513 × |
81513 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand five hundred and thirteen |
| Binary (base 2) | 10011111001101001 |
| Octal (base 8) | 237151 |
| Hexadecimal (base 16) | 13E69 |
| Base 3 | 11010211000 |
| As time | 81513 seconds = 22 h 38 min 33 s |
Is 81513 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 (81513 ÷ 3 = 27171) | 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 3) | 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 5) | 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 | Yes (81513 ÷ 9 = 9057) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | 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 81513 a prime number?
No. 81513 = × 3019, so it is divisible by 3.
What are the factors of 81513?
1, 3, 9, 27, 3019, 9057, 27171, 81513.
What is 81513 in binary?
10011111001101001 (hexadecimal 13E69, octal 237151).
What is the square root of 81513?
About 285.5048, exactly 3√9057.
Is 81513 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 81513?
81513 is a happy number: repeatedly adding the squares of its digits reaches 1.