The number 13805
13805 is a composite number with 8 divisors. Its prime factorisation is 5 × 11 × 251. Divisors (8): 1, 5, 11, 55, 251, 1255, 2761, 13805.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
13805 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
13805 is composite. Its prime factorisation is
- 3
The divisors add up to 18144; without 13805 itself that is 4339, so 13805 is deficient (4339 is less than 13805). Euler's totient φ(13805) = 10000 numbers up to 13805 share no factor with it.
- 4
The digits of 13805 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 58 steps to reach 1.
LaTeX source of the formulas on this page
\[ 13805 = 5 \times 11 \times 251 \]
13805 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 18144 |
| Euler totient φ(n) | 10000 |
| Square | 190578025 |
| Cube | 2630929635125 |
| Square root | 117.494681 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 58 |
| Scientific notation | 1.3805 × |
13805 in other forms
| Form | Value |
|---|---|
| In words | thirteen thousand eight hundred and five |
| Binary (base 2) | 11010111101101 |
| Octal (base 8) | 32755 |
| Hexadecimal (base 16) | 35ED |
| Base 3 | 200221022 |
| As time | 13805 seconds = 3 h 50 min 5 s |
Is 13805 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (13805 ÷ 5 = 2761) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (13805 ÷ 11 = 1255) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 13805 a prime number?
No. 13805 = 5 × 11 × 251, so it is divisible by 5.
What are the factors of 13805?
1, 5, 11, 55, 251, 1255, 2761, 13805.
What is 13805 in binary?
11010111101101 (hexadecimal 35ED, octal 32755).
What is the square root of 13805?
About 117.4947.
Is 13805 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 13805?
It is a composite number with 8 divisors.