The number 81138
81138 is a composite number with 8 divisors. Its prime factorisation is 2 × 3 × 13523. Divisors (8): 1, 2, 3, 6, 13523, 27046, 40569, 81138.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81138: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81138 is composite. Its prime factorisation is
- 3
The divisors add up to 162288; without 81138 itself that is 81150, so 81138 is abundant (81150 is more than 81138). Euler's totient φ(81138) = 27044 numbers up to 81138 share no factor with it.
- 4
The digits of 81138 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 63 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81138 = 2 \times 3 \times 13523 \]
81138 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 162288 |
| Euler totient φ(n) | 27044 |
| Square | 6583375044 |
| Cube | 534161884320072 |
| Square root | 284.847328 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 63 |
| Scientific notation | 8.1138 × |
81138 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand one hundred and thirty-eight |
| Binary (base 2) | 10011110011110010 |
| Octal (base 8) | 236362 |
| Hexadecimal (base 16) | 13CF2 |
| Base 3 | 11010022010 |
| As time | 81138 seconds = 22 h 32 min 18 s |
Is 81138 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81138 ÷ 2 = 40569) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81138 ÷ 3 = 27046) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | 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 | Yes (81138 ÷ 6 = 13523) | 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 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81138 a prime number?
No. 81138 = 2 × 3 × 13523, so it is divisible by 2.
What are the factors of 81138?
1, 2, 3, 6, 13523, 27046, 40569, 81138.
What is 81138 in binary?
10011110011110010 (hexadecimal 13CF2, octal 236362).
What is the square root of 81138?
About 284.8473.
Is 81138 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 81138?
81138 is a happy number: repeatedly adding the squares of its digits reaches 1.