The number 21842
21842 is a composite number with 8 divisors. Its prime factorisation is 2 × 67 × 163. Divisors (8): 1, 2, 67, 134, 163, 326, 10921, 21842.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21842 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21842 is composite. Its prime factorisation is
- 3
The divisors add up to 33456; without 21842 itself that is 11614, so 21842 is deficient (11614 is less than 21842). Euler's totient φ(21842) = 10692 numbers up to 21842 share no factor with it.
- 4
The digits of 21842 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 162 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21842 = 2 \times 67 \times 163 \]
21842 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 33456 |
| Euler totient φ(n) | 10692 |
| Square | 477072964 |
| Cube | 10420227679688 |
| Square root | 147.790392 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.1842 × |
21842 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and forty-two |
| Binary (base 2) | 101010101010010 |
| Octal (base 8) | 52522 |
| Hexadecimal (base 16) | 5552 |
| Base 3 | 1002221222 |
| As time | 21842 seconds = 6 h 4 min 2 s |
Is 21842 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21842 ÷ 2 = 10921) | 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 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 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 8) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21842 a prime number?
No. 21842 = 2 × 67 × 163, so it is divisible by 2.
What are the factors of 21842?
1, 2, 67, 134, 163, 326, 10921, 21842.
What is 21842 in binary?
101010101010010 (hexadecimal 5552, octal 52522).
What is the square root of 21842?
About 147.7904.
Is 21842 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 21842?
It is a composite number with 8 divisors.