The number 20409
20409 is a composite number with 4 divisors. Its prime factorisation is 3 × 6803. Divisors (4): 1, 3, 6803, 20409.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20409: a semiprime: 3 × 6803, the product of two primes.
- 2
20409 is composite. Its prime factorisation is
- 3
The divisors add up to 27216; without 20409 itself that is 6807, so 20409 is deficient (6807 is less than 20409). Euler's totient φ(20409) = 13604 numbers up to 20409 share no factor with it.
- 4
The digits of 20409 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 87 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20409 = 3 \times 6803 \]
20409 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 27216 |
| Euler totient φ(n) | 13604 |
| Square | 416527281 |
| Cube | 8500905277929 |
| Square root | 142.860071 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 87 |
| Scientific notation | 2.0409 × |
20409 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand four hundred and nine |
| Binary (base 2) | 100111110111001 |
| Octal (base 8) | 47671 |
| Hexadecimal (base 16) | 4FB9 |
| Base 3 | 1000222220 |
| As time | 20409 seconds = 5 h 40 min 9 s |
Is 20409 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 | Yes (20409 ÷ 3 = 6803) | 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 3) | 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 | No (remainder 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | 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 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20409 a prime number?
No. 20409 = 3 × 6803, so it is divisible by 3.
What are the factors of 20409?
1, 3, 6803, 20409.
What is 20409 in binary?
100111110111001 (hexadecimal 4FB9, octal 47671).
What is the square root of 20409?
About 142.8601.
Is 20409 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 20409?
20409 is a semiprime: 3 × 6803, the product of two primes.