The number 87728
87728 is a composite number with 10 divisors. Its prime factorisation is × 5483. Divisors (10): 1, 2, 4, 8, 16, 5483, 10966, 21932, 43864, 87728.
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How to work it out
- 1
What is special about 87728: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
87728 is composite. Its prime factorisation is
- 3
The divisors add up to 170004; without 87728 itself that is 82276, so 87728 is deficient (82276 is less than 87728). Euler's totient φ(87728) = 43856 numbers up to 87728 share no factor with it.
- 4
The digits of 87728 add up to 32, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 120 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87728 = 2^{4} \times 5483 \]87728 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 10 |
| Sum of divisors | 170004 |
| Euler totient φ(n) | 43856 |
| Square | 7696201984 |
| Cube | 675172407652352 |
| Square root | 296.189129 (= 4√5483) |
| Digit sum / digital root | 32 / 5 |
| Collatz steps to 1 | 120 |
| Scientific notation | 8.7728 × |
87728 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand seven hundred and twenty-eight |
| Binary (base 2) | 10101011010110000 |
| Octal (base 8) | 253260 |
| Hexadecimal (base 16) | 156B0 |
| Base 3 | 11110100012 |
| As time | 87728 seconds = 24 h 22 min 8 s |
Is 87728 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (87728 ÷ 2 = 43864) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (87728 ÷ 4 = 21932) | 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 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 | Yes (87728 ÷ 8 = 10966) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87728 a prime number?
No. 87728 = × 5483, so it is divisible by 2.
What are the factors of 87728?
1, 2, 4, 8, 16, 5483, 10966, 21932, 43864, 87728.
What is 87728 in binary?
10101011010110000 (hexadecimal 156B0, octal 253260).
What is the square root of 87728?
About 296.1891, exactly 4√5483.
Is 87728 divisible by 3?
No. Its digits add up to 32, which is not a multiple of 3.
What is special about the number 87728?
87728 is a happy number: repeatedly adding the squares of its digits reaches 1.