The number 21829
21829 is a composite number with 4 divisors. Its prime factorisation is 83 × 263. Divisors (4): 1, 83, 263, 21829.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21829: a semiprime: 83 × 263, the product of two primes.
- 2
21829 is composite. Its prime factorisation is
- 3
The divisors add up to 22176; without 21829 itself that is 347, so 21829 is deficient (347 is less than 21829). Euler's totient φ(21829) = 21484 numbers up to 21829 share no factor with it.
- 4
The digits of 21829 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 69 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21829 = 83 \times 263 \]
21829 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22176 |
| Euler totient φ(n) | 21484 |
| Square | 476505241 |
| Cube | 10401632905789 |
| Square root | 147.746404 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 69 |
| Scientific notation | 2.1829 × |
21829 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and twenty-nine |
| Binary (base 2) | 101010101000101 |
| Octal (base 8) | 52505 |
| Hexadecimal (base 16) | 5545 |
| Base 3 | 1002221111 |
| As time | 21829 seconds = 6 h 3 min 49 s |
Is 21829 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21829 a prime number?
No. 21829 = 83 × 263, so it is divisible by 83.
What are the factors of 21829?
1, 83, 263, 21829.
What is 21829 in binary?
101010101000101 (hexadecimal 5545, octal 52505).
What is the square root of 21829?
About 147.7464.
Is 21829 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 21829?
21829 is a semiprime: 83 × 263, the product of two primes.