The number 87172
87172 is a composite number with 24 divisors. Its prime factorisation is × 19 × 31 × 37. Divisors (24): 1, 2, 4, 19, 31, 37, 38, 62, 74, 76, 124, 148, 589, 703, 1147, 1178 … 87172.
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How to work it out
- 1
What is special about 87172: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
87172 is composite. Its prime factorisation is
- 3
The divisors add up to 170240; without 87172 itself that is 83068, so 87172 is deficient (83068 is less than 87172). Euler's totient φ(87172) = 38880 numbers up to 87172 share no factor with it.
- 4
The digits of 87172 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 58 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87172 = 2^{2} \times 19 \times 31 \times 37 \]87172 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 170240 |
| Euler totient φ(n) | 38880 |
| Square | 7598957584 |
| Cube | 662416330512448 |
| Square root | 295.249047 (= 2√21793) |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 58 |
| Scientific notation | 8.7172 × |
87172 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand one hundred and seventy-two |
| Binary (base 2) | 10101010010000100 |
| Octal (base 8) | 252204 |
| Hexadecimal (base 16) | 15484 |
| Base 3 | 11102120121 |
| As time | 87172 seconds = 24 h 12 min 52 s |
Is 87172 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (87172 ÷ 2 = 43586) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (87172 ÷ 4 = 21793) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87172 a prime number?
No. 87172 = × 19 × 31 × 37, so it is divisible by 2.
What are the factors of 87172?
1, 2, 4, 19, 31, 37, 38, 62, 74, 76, 124, 148, 589, 703, 1147, 1178, 1406, 2294, 2356, 2812, 4588, 21793, 43586, 87172.
What is 87172 in binary?
10101010010000100 (hexadecimal 15484, octal 252204).
What is the square root of 87172?
About 295.2490, exactly 2√21793.
Is 87172 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 87172?
87172 is a happy number: repeatedly adding the squares of its digits reaches 1.