The number 42561
42561 is a composite number with 6 divisors. Its prime factorisation is × 4729. Divisors (6): 1, 3, 9, 4729, 14187, 42561.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42561: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
42561 is composite. Its prime factorisation is
- 3
The divisors add up to 61490; without 42561 itself that is 18929, so 42561 is deficient (18929 is less than 42561). Euler's totient φ(42561) = 28368 numbers up to 42561 share no factor with it.
- 4
The digits of 42561 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 101 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42561 = 3^{2} \times 4729 \]42561 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 61490 |
| Euler totient φ(n) | 28368 |
| Square | 1811438721 |
| Cube | 77096643404481 |
| Square root | 206.303175 (= 3√4729) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 101 |
| Scientific notation | 4.2561 × |
42561 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand five hundred and sixty-one |
| Binary (base 2) | 1010011001000001 |
| Octal (base 8) | 123101 |
| Hexadecimal (base 16) | A641 |
| Base 3 | 2011101100 |
| As time | 42561 seconds = 11 h 49 min 21 s |
Is 42561 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 (42561 ÷ 3 = 14187) | 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 3) | 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 | Yes (42561 ÷ 9 = 4729) | 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 2) | 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 42561 a prime number?
No. 42561 = × 4729, so it is divisible by 3.
What are the factors of 42561?
1, 3, 9, 4729, 14187, 42561.
What is 42561 in binary?
1010011001000001 (hexadecimal A641, octal 123101).
What is the square root of 42561?
About 206.3032, exactly 3√4729.
Is 42561 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 42561?
42561 is a happy number: repeatedly adding the squares of its digits reaches 1.