The number 42811
42811 is a composite number with 4 divisors. Its prime factorisation is 31 × 1381. Divisors (4): 1, 31, 1381, 42811.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42811: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 31 × 1381, the product of two primes.
- 2
42811 is composite. Its prime factorisation is
- 3
The divisors add up to 44224; without 42811 itself that is 1413, so 42811 is deficient (1413 is less than 42811). Euler's totient φ(42811) = 41400 numbers up to 42811 share no factor with it.
- 4
The digits of 42811 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 49 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42811 = 31 \times 1381 \]
42811 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 44224 |
| Euler totient φ(n) | 41400 |
| Square | 1832781721 |
| Cube | 78463218257731 |
| Square root | 206.908192 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 49 |
| Scientific notation | 4.2811 × |
42811 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand eight hundred and eleven |
| Binary (base 2) | 1010011100111011 |
| Octal (base 8) | 123473 |
| Hexadecimal (base 16) | A73B |
| Base 3 | 2011201121 |
| As time | 42811 seconds = 11 h 53 min 31 s |
Is 42811 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 3) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 3) | 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 1) | 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 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 42811 a prime number?
No. 42811 = 31 × 1381, so it is divisible by 31.
What are the factors of 42811?
1, 31, 1381, 42811.
What is 42811 in binary?
1010011100111011 (hexadecimal A73B, octal 123473).
What is the square root of 42811?
About 206.9082.
Is 42811 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 42811?
42811 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 31 × 1381, the product of two primes.