The number 87409
87409 is a composite number with 4 divisors. Its prime factorisation is 7 × 12487. Divisors (4): 1, 7, 12487, 87409.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 87409: a semiprime: 7 × 12487, the product of two primes.
- 2
87409 is composite. Its prime factorisation is
- 3
The divisors add up to 99904; without 87409 itself that is 12495, so 87409 is deficient (12495 is less than 87409). Euler's totient φ(87409) = 74916 numbers up to 87409 share no factor with it.
- 4
The digits of 87409 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 120 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87409 = 7 \times 12487 \]
87409 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 99904 |
| Euler totient φ(n) | 74916 |
| Square | 7640333281 |
| Cube | 667833891758929 |
| Square root | 295.650131 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 120 |
| Scientific notation | 8.7409 × |
87409 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand four hundred and nine |
| Binary (base 2) | 10101010101110001 |
| Octal (base 8) | 252561 |
| Hexadecimal (base 16) | 15571 |
| Base 3 | 11102220101 |
| As time | 87409 seconds = 24 h 16 min 49 s |
Is 87409 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 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (87409 ÷ 7 = 12487) | 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 | No (remainder 1) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87409 a prime number?
No. 87409 = 7 × 12487, so it is divisible by 7.
What are the factors of 87409?
1, 7, 12487, 87409.
What is 87409 in binary?
10101010101110001 (hexadecimal 15571, octal 252561).
What is the square root of 87409?
About 295.6501.
Is 87409 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 87409?
87409 is a semiprime: 7 × 12487, the product of two primes.