The number 21124
21124 is a composite number with 6 divisors. Its prime factorisation is × 5281. Divisors (6): 1, 2, 4, 5281, 10562, 21124.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21124 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21124 is composite. Its prime factorisation is
- 3
The divisors add up to 36974; without 21124 itself that is 15850, so 21124 is deficient (15850 is less than 21124). Euler's totient φ(21124) = 10560 numbers up to 21124 share no factor with it.
- 4
The digits of 21124 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21124 = 2^{2} \times 5281 \]21124 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 36974 |
| Euler totient φ(n) | 10560 |
| Square | 446223376 |
| Cube | 9426022594624 |
| Square root | 145.340978 (= 2√5281) |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1124 × |
21124 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and twenty-four |
| Binary (base 2) | 101001010000100 |
| Octal (base 8) | 51204 |
| Hexadecimal (base 16) | 5284 |
| Base 3 | 1001222101 |
| As time | 21124 seconds = 5 h 52 min 4 s |
Is 21124 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21124 ÷ 2 = 10562) | 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 | Yes (21124 ÷ 4 = 5281) | 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 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 4) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21124 a prime number?
No. 21124 = × 5281, so it is divisible by 2.
What are the factors of 21124?
1, 2, 4, 5281, 10562, 21124.
What is 21124 in binary?
101001010000100 (hexadecimal 5284, octal 51204).
What is the square root of 21124?
About 145.3410, exactly 2√5281.
Is 21124 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21124?
It is a composite number with 6 divisors.