The number 18105
18105 is a composite number with 16 divisors. Its prime factorisation is 3 × 5 × 17 × 71. Divisors (16): 1, 3, 5, 15, 17, 51, 71, 85, 213, 255, 355, 1065, 1207, 3621, 6035, 18105.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18105: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 15.
- 2
18105 is composite. Its prime factorisation is
- 3
The divisors add up to 31104; without 18105 itself that is 12999, so 18105 is deficient (12999 is less than 18105). Euler's totient φ(18105) = 8960 numbers up to 18105 share no factor with it.
- 4
The digits of 18105 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 40 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18105 = 3 \times 5 \times 17 \times 71 \]
18105 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 31104 |
| Euler totient φ(n) | 8960 |
| Square | 327791025 |
| Cube | 5934656507625 |
| Square root | 134.554822 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 40 |
| Scientific notation | 1.8105 × |
18105 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand one hundred and five |
| Binary (base 2) | 100011010111001 |
| Octal (base 8) | 43271 |
| Hexadecimal (base 16) | 46B9 |
| Base 3 | 220211120 |
| As time | 18105 seconds = 5 h 1 min 45 s |
Is 18105 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 (18105 ÷ 3 = 6035) | 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 (18105 ÷ 5 = 3621) | 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 3) | 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 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | 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 18105 a prime number?
No. 18105 = 3 × 5 × 17 × 71, so it is divisible by 3.
What are the factors of 18105?
1, 3, 5, 15, 17, 51, 71, 85, 213, 255, 355, 1065, 1207, 3621, 6035, 18105.
What is 18105 in binary?
100011010111001 (hexadecimal 46B9, octal 43271).
What is the square root of 18105?
About 134.5548.
Is 18105 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 18105?
18105 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 15.