The number 18001
18001 is a composite number with 4 divisors. Its prime factorisation is 47 × 383. Divisors (4): 1, 47, 383, 18001.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18001: a semiprime: 47 × 383, the product of two primes.
- 2
18001 is composite. Its prime factorisation is
- 3
The divisors add up to 18432; without 18001 itself that is 431, so 18001 is deficient (431 is less than 18001). Euler's totient φ(18001) = 17572 numbers up to 18001 share no factor with it.
- 4
The digits of 18001 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 141 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18001 = 47 \times 383 \]
18001 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 18432 |
| Euler totient φ(n) | 17572 |
| Square | 324036001 |
| Cube | 5832972054001 |
| Square root | 134.167805 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 141 |
| Scientific notation | 1.8001 × |
18001 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand and one |
| Binary (base 2) | 100011001010001 |
| Octal (base 8) | 43121 |
| Hexadecimal (base 16) | 4651 |
| Base 3 | 220200201 |
| As time | 18001 seconds = 5 h 0 min 1 s |
Is 18001 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 1) | 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 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 1) | 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 5) | 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 18001 a prime number?
No. 18001 = 47 × 383, so it is divisible by 47.
What are the factors of 18001?
1, 47, 383, 18001.
What is 18001 in binary?
100011001010001 (hexadecimal 4651, octal 43121).
What is the square root of 18001?
About 134.1678.
Is 18001 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 18001?
18001 is a semiprime: 47 × 383, the product of two primes.