The number 21827
21827 is a composite number with 8 divisors. Its prime factorisation is 13 × 23 × 73. Divisors (8): 1, 13, 23, 73, 299, 949, 1679, 21827.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21827 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21827 is composite. Its prime factorisation is
- 3
The divisors add up to 24864; without 21827 itself that is 3037, so 21827 is deficient (3037 is less than 21827). Euler's totient φ(21827) = 19008 numbers up to 21827 share no factor with it.
- 4
The digits of 21827 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 131 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21827 = 13 \times 23 \times 73 \]
21827 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 24864 |
| Euler totient φ(n) | 19008 |
| Square | 476417929 |
| Cube | 10398774136283 |
| Square root | 147.739636 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 131 |
| Scientific notation | 2.1827 × |
21827 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and twenty-seven |
| Binary (base 2) | 101010101000011 |
| Octal (base 8) | 52503 |
| Hexadecimal (base 16) | 5543 |
| Base 3 | 1002221102 |
| As time | 21827 seconds = 6 h 3 min 47 s |
Is 21827 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 2) | 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 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21827 a prime number?
No. 21827 = 13 × 23 × 73, so it is divisible by 13.
What are the factors of 21827?
1, 13, 23, 73, 299, 949, 1679, 21827.
What is 21827 in binary?
101010101000011 (hexadecimal 5543, octal 52503).
What is the square root of 21827?
About 147.7396.
Is 21827 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 21827?
It is a composite number with 8 divisors.