The number 42805
42805 is a composite number with 8 divisors. Its prime factorisation is 5 × 7 × 1223. Divisors (8): 1, 5, 7, 35, 1223, 6115, 8561, 42805.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42805: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
42805 is composite. Its prime factorisation is
- 3
The divisors add up to 58752; without 42805 itself that is 15947, so 42805 is deficient (15947 is less than 42805). Euler's totient φ(42805) = 29328 numbers up to 42805 share no factor with it.
- 4
The digits of 42805 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 49 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42805 = 5 \times 7 \times 1223 \]
42805 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 58752 |
| Euler totient φ(n) | 29328 |
| Square | 1832268025 |
| Cube | 78430232810125 |
| Square root | 206.893693 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 49 |
| Scientific notation | 4.2805 × |
42805 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand eight hundred and five |
| Binary (base 2) | 1010011100110101 |
| Octal (base 8) | 123465 |
| Hexadecimal (base 16) | A735 |
| Base 3 | 2011201101 |
| As time | 42805 seconds = 11 h 53 min 25 s |
Is 42805 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 | Yes (42805 ÷ 5 = 8561) | 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 | Yes (42805 ÷ 7 = 6115) | 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 1) | 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 4) | 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 42805 a prime number?
No. 42805 = 5 × 7 × 1223, so it is divisible by 5.
What are the factors of 42805?
1, 5, 7, 35, 1223, 6115, 8561, 42805.
What is 42805 in binary?
1010011100110101 (hexadecimal A735, octal 123465).
What is the square root of 42805?
About 206.8937.
Is 42805 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 42805?
42805 is a happy number: repeatedly adding the squares of its digits reaches 1.