The number 87129
87129 is a composite number with 16 divisors. Its prime factorisation is × 7 × 461. Divisors (16): 1, 3, 7, 9, 21, 27, 63, 189, 461, 1383, 3227, 4149, 9681, 12447, 29043, 87129.
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How to work it out
- 1
What is special about 87129: a Harshad number: divisible by its digit sum 27.
- 2
87129 is composite. Its prime factorisation is
- 3
The divisors add up to 147840; without 87129 itself that is 60711, so 87129 is deficient (60711 is less than 87129). Euler's totient φ(87129) = 49680 numbers up to 87129 share no factor with it.
- 4
The digits of 87129 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 71 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87129 = 3^{3} \times 7 \times 461 \]87129 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 147840 |
| Euler totient φ(n) | 49680 |
| Square | 7591462641 |
| Cube | 661436548447689 |
| Square root | 295.176219 (= 3√9681) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 71 |
| Scientific notation | 8.7129 × |
87129 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand one hundred and twenty-nine |
| Binary (base 2) | 10101010001011001 |
| Octal (base 8) | 252131 |
| Hexadecimal (base 16) | 15459 |
| Base 3 | 11102112000 |
| As time | 87129 seconds = 24 h 12 min 9 s |
Is 87129 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 (87129 ÷ 3 = 29043) | 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 4) | 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 | Yes (87129 ÷ 7 = 12447) | 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 (87129 ÷ 9 = 9681) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 87129 a prime number?
No. 87129 = × 7 × 461, so it is divisible by 3.
What are the factors of 87129?
1, 3, 7, 9, 21, 27, 63, 189, 461, 1383, 3227, 4149, 9681, 12447, 29043, 87129.
What is 87129 in binary?
10101010001011001 (hexadecimal 15459, octal 252131).
What is the square root of 87129?
About 295.1762, exactly 3√9681.
Is 87129 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 87129?
87129 is a Harshad number: divisible by its digit sum 27.