The number 21837
21837 is a composite number with 8 divisors. Its prime factorisation is 3 × 29 × 251. Divisors (8): 1, 3, 29, 87, 251, 753, 7279, 21837.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21837 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21837 is composite. Its prime factorisation is
- 3
The divisors add up to 30240; without 21837 itself that is 8403, so 21837 is deficient (8403 is less than 21837). Euler's totient φ(21837) = 14000 numbers up to 21837 share no factor with it.
- 4
The digits of 21837 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 162 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21837 = 3 \times 29 \times 251 \]
21837 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 30240 |
| Euler totient φ(n) | 14000 |
| Square | 476854569 |
| Cube | 10413073223253 |
| Square root | 147.773475 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.1837 × |
21837 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and thirty-seven |
| Binary (base 2) | 101010101001101 |
| Octal (base 8) | 52515 |
| Hexadecimal (base 16) | 554D |
| Base 3 | 1002221210 |
| As time | 21837 seconds = 6 h 3 min 57 s |
Is 21837 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 | Yes (21837 ÷ 3 = 7279) | 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 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 3) | 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 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21837 a prime number?
No. 21837 = 3 × 29 × 251, so it is divisible by 3.
What are the factors of 21837?
1, 3, 29, 87, 251, 753, 7279, 21837.
What is 21837 in binary?
101010101001101 (hexadecimal 554D, octal 52515).
What is the square root of 21837?
About 147.7735.
Is 21837 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 21837?
It is a composite number with 8 divisors.