The number 42505
42505 is a composite number with 4 divisors. Its prime factorisation is 5 × 8501. Divisors (4): 1, 5, 8501, 42505.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42505: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 5 × 8501, the product of two primes.
- 2
42505 is composite. Its prime factorisation is
- 3
The divisors add up to 51012; without 42505 itself that is 8507, so 42505 is deficient (8507 is less than 42505). Euler's totient φ(42505) = 34000 numbers up to 42505 share no factor with it.
- 4
The digits of 42505 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 238 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42505 = 5 \times 8501 \]
42505 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 51012 |
| Euler totient φ(n) | 34000 |
| Square | 1806675025 |
| Cube | 76792721937625 |
| Square root | 206.167408 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 238 |
| Scientific notation | 4.2505 × |
42505 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand five hundred and five |
| Binary (base 2) | 1010011000001001 |
| Octal (base 8) | 123011 |
| Hexadecimal (base 16) | A609 |
| Base 3 | 2011022021 |
| As time | 42505 seconds = 11 h 48 min 25 s |
Is 42505 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 (42505 ÷ 5 = 8501) | 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 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 1) | 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 42505 a prime number?
No. 42505 = 5 × 8501, so it is divisible by 5.
What are the factors of 42505?
1, 5, 8501, 42505.
What is 42505 in binary?
1010011000001001 (hexadecimal A609, octal 123011).
What is the square root of 42505?
About 206.1674.
Is 42505 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 42505?
42505 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 5 × 8501, the product of two primes.