The number 18409
18409 is a composite number with 4 divisors. Its prime factorisation is 41 × 449. Divisors (4): 1, 41, 449, 18409.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18409: a semiprime: 41 × 449, the product of two primes.
- 2
18409 is composite. Its prime factorisation is
- 3
The divisors add up to 18900; without 18409 itself that is 491, so 18409 is deficient (491 is less than 18409). Euler's totient φ(18409) = 17920 numbers up to 18409 share no factor with it.
- 4
The digits of 18409 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 66 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18409 = 41 \times 449 \]
18409 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 18900 |
| Euler totient φ(n) | 17920 |
| Square | 338891281 |
| Cube | 6238649591929 |
| Square root | 135.679770 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 66 |
| Scientific notation | 1.8409 × |
18409 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand four hundred and nine |
| Binary (base 2) | 100011111101001 |
| Octal (base 8) | 43751 |
| Hexadecimal (base 16) | 47E9 |
| Base 3 | 221020211 |
| As time | 18409 seconds = 5 h 6 min 49 s |
Is 18409 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 | No (remainder 6) | 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 4) | 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 6) | 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 18409 a prime number?
No. 18409 = 41 × 449, so it is divisible by 41.
What are the factors of 18409?
1, 41, 449, 18409.
What is 18409 in binary?
100011111101001 (hexadecimal 47E9, octal 43751).
What is the square root of 18409?
About 135.6798.
Is 18409 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 18409?
18409 is a semiprime: 41 × 449, the product of two primes.