The number 20842
20842 is a composite number with 8 divisors. Its prime factorisation is 2 × 17 × 613. Divisors (8): 1, 2, 17, 34, 613, 1226, 10421, 20842.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
20842 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
20842 is composite. Its prime factorisation is
- 3
The divisors add up to 33156; without 20842 itself that is 12314, so 20842 is deficient (12314 is less than 20842). Euler's totient φ(20842) = 9792 numbers up to 20842 share no factor with it.
- 4
The digits of 20842 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 105 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20842 = 2 \times 17 \times 613 \]
20842 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 33156 |
| Euler totient φ(n) | 9792 |
| Square | 434388964 |
| Cube | 9053534787688 |
| Square root | 144.367586 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 105 |
| Scientific notation | 2.0842 × |
20842 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand eight hundred and forty-two |
| Binary (base 2) | 101000101101010 |
| Octal (base 8) | 50552 |
| Hexadecimal (base 16) | 516A |
| Base 3 | 1001120221 |
| As time | 20842 seconds = 5 h 47 min 22 s |
Is 20842 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (20842 ÷ 2 = 10421) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 2) | 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 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20842 a prime number?
No. 20842 = 2 × 17 × 613, so it is divisible by 2.
What are the factors of 20842?
1, 2, 17, 34, 613, 1226, 10421, 20842.
What is 20842 in binary?
101000101101010 (hexadecimal 516A, octal 50552).
What is the square root of 20842?
About 144.3676.
Is 20842 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 20842?
It is a composite number with 8 divisors.