The number 42005
42005 is a composite number with 8 divisors. Its prime factorisation is 5 × 31 × 271. Divisors (8): 1, 5, 31, 155, 271, 1355, 8401, 42005.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
42005 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
42005 is composite. Its prime factorisation is
- 3
The divisors add up to 52224; without 42005 itself that is 10219, so 42005 is deficient (10219 is less than 42005). Euler's totient φ(42005) = 32400 numbers up to 42005 share no factor with it.
- 4
The digits of 42005 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 31 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42005 = 5 \times 31 \times 271 \]
42005 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 52224 |
| Euler totient φ(n) | 32400 |
| Square | 1764420025 |
| Cube | 74114463150125 |
| Square root | 204.951214 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 31 |
| Scientific notation | 4.2005 × |
42005 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand and five |
| Binary (base 2) | 1010010000010101 |
| Octal (base 8) | 122025 |
| Hexadecimal (base 16) | A415 |
| Base 3 | 2010121202 |
| As time | 42005 seconds = 11 h 40 min 5 s |
Is 42005 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 (42005 ÷ 5 = 8401) | 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 5) | 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 2) | 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 7) | 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 42005 a prime number?
No. 42005 = 5 × 31 × 271, so it is divisible by 5.
What are the factors of 42005?
1, 5, 31, 155, 271, 1355, 8401, 42005.
What is 42005 in binary?
1010010000010101 (hexadecimal A415, octal 122025).
What is the square root of 42005?
About 204.9512.
Is 42005 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 42005?
It is a composite number with 8 divisors.