The number 87431
87431 is a composite number with 8 divisors. Its prime factorisation is 17 × 37 × 139. Divisors (8): 1, 17, 37, 139, 629, 2363, 5143, 87431.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 87431: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
87431 is composite. Its prime factorisation is
- 3
The divisors add up to 95760; without 87431 itself that is 8329, so 87431 is deficient (8329 is less than 87431). Euler's totient φ(87431) = 79488 numbers up to 87431 share no factor with it.
- 4
The digits of 87431 add up to 23, 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
\[ 87431 = 17 \times 37 \times 139 \]
87431 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 95760 |
| Euler totient φ(n) | 79488 |
| Square | 7644179761 |
| Cube | 668338280683991 |
| Square root | 295.687335 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 120 |
| Scientific notation | 8.7431 × |
87431 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand four hundred and thirty-one |
| Binary (base 2) | 10101010110000111 |
| Octal (base 8) | 252607 |
| Hexadecimal (base 16) | 15587 |
| Base 3 | 11102221012 |
| As time | 87431 seconds = 24 h 17 min 11 s |
Is 87431 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 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 5) | 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 7) | 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 1) | 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 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87431 a prime number?
No. 87431 = 17 × 37 × 139, so it is divisible by 17.
What are the factors of 87431?
1, 17, 37, 139, 629, 2363, 5143, 87431.
What is 87431 in binary?
10101010110000111 (hexadecimal 15587, octal 252607).
What is the square root of 87431?
About 295.6873.
Is 87431 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 87431?
87431 is a happy number: repeatedly adding the squares of its digits reaches 1.