The number 81378
81378 is a composite number with 32 divisors. Its prime factorisation is 2 × × 11 × 137. Divisors (32): 1, 2, 3, 6, 9, 11, 18, 22, 27, 33, 54, 66, 99, 137, 198, 274 … 81378.
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How to work it out
- 1
What is special about 81378: a Harshad number: divisible by its digit sum 27.
- 2
81378 is composite. Its prime factorisation is
- 3
The divisors add up to 198720; without 81378 itself that is 117342, so 81378 is abundant (117342 is more than 81378). Euler's totient φ(81378) = 24480 numbers up to 81378 share no factor with it.
- 4
The digits of 81378 add up to 27, 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
\[ 81378 = 2 \times 3^{3} \times 11 \times 137 \]81378 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 198720 |
| Euler totient φ(n) | 24480 |
| Square | 6622378884 |
| Cube | 538915948822152 |
| Square root | 285.268295 (= 3√9042) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 37 |
| Scientific notation | 8.1378 × |
81378 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand three hundred and seventy-eight |
| Binary (base 2) | 10011110111100010 |
| Octal (base 8) | 236742 |
| Hexadecimal (base 16) | 13DE2 |
| Base 3 | 11010122000 |
| As time | 81378 seconds = 22 h 36 min 18 s |
Is 81378 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81378 ÷ 2 = 40689) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81378 ÷ 3 = 27126) | 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 (81378 ÷ 6 = 13563) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 | Yes (81378 ÷ 9 = 9042) | 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 | Yes (81378 ÷ 11 = 7398) | 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 81378 a prime number?
No. 81378 = 2 × × 11 × 137, so it is divisible by 2.
What are the factors of 81378?
1, 2, 3, 6, 9, 11, 18, 22, 27, 33, 54, 66, 99, 137, 198, 274, 297, 411, 594, 822, 1233, 1507, 2466, 3014, 3699, 4521, 7398, 9042, 13563, 27126, 40689, 81378.
What is 81378 in binary?
10011110111100010 (hexadecimal 13DE2, octal 236742).
What is the square root of 81378?
About 285.2683, exactly 3√9042.
Is 81378 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 81378?
81378 is a Harshad number: divisible by its digit sum 27.