The number 87561
87561 is a composite number with 20 divisors. Its prime factorisation is × 23 × 47. Divisors (20): 1, 3, 9, 23, 27, 47, 69, 81, 141, 207, 423, 621, 1081, 1269, 1863, 3243 … 87561.
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How to work it out
- 1
What is special about 87561: a Harshad number: divisible by its digit sum 27.
- 2
87561 is composite. Its prime factorisation is
- 3
The divisors add up to 139392; without 87561 itself that is 51831, so 87561 is deficient (51831 is less than 87561). Euler's totient φ(87561) = 54648 numbers up to 87561 share no factor with it.
- 4
The digits of 87561 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 102 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87561 = 3^{4} \times 23 \times 47 \]87561 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 139392 |
| Euler totient φ(n) | 54648 |
| Square | 7666928721 |
| Cube | 671323945739481 |
| Square root | 295.907080 (= 9√1081) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 102 |
| Scientific notation | 8.7561 × |
87561 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand five hundred and sixty-one |
| Binary (base 2) | 10101011000001001 |
| Octal (base 8) | 253011 |
| Hexadecimal (base 16) | 15609 |
| Base 3 | 11110010000 |
| As time | 87561 seconds = 24 h 19 min 21 s |
Is 87561 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 (87561 ÷ 3 = 29187) | 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 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 (87561 ÷ 9 = 9729) | 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 1) | 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 87561 a prime number?
No. 87561 = × 23 × 47, so it is divisible by 3.
What are the factors of 87561?
1, 3, 9, 23, 27, 47, 69, 81, 141, 207, 423, 621, 1081, 1269, 1863, 3243, 3807, 9729, 29187, 87561.
What is 87561 in binary?
10101011000001001 (hexadecimal 15609, octal 253011).
What is the square root of 87561?
About 295.9071, exactly 9√1081.
Is 87561 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 87561?
87561 is a Harshad number: divisible by its digit sum 27.