The number 21126
21126 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 7 × 503. Divisors (16): 1, 2, 3, 6, 7, 14, 21, 42, 503, 1006, 1509, 3018, 3521, 7042, 10563, 21126.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21126 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21126 is composite. Its prime factorisation is
- 3
The divisors add up to 48384; without 21126 itself that is 27258, so 21126 is abundant (27258 is more than 21126). Euler's totient φ(21126) = 6024 numbers up to 21126 share no factor with it.
- 4
The digits of 21126 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21126 = 2 \times 3 \times 7 \times 503 \]
21126 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 48384 |
| Euler totient φ(n) | 6024 |
| Square | 446307876 |
| Cube | 9428700188376 |
| Square root | 145.347859 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1126 × |
21126 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and twenty-six |
| Binary (base 2) | 101001010000110 |
| Octal (base 8) | 51206 |
| Hexadecimal (base 16) | 5286 |
| Base 3 | 1001222110 |
| As time | 21126 seconds = 5 h 52 min 6 s |
Is 21126 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21126 ÷ 2 = 10563) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21126 ÷ 3 = 7042) | 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 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21126 ÷ 6 = 3521) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21126 ÷ 7 = 3018) | 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 6) | 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 6) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21126 a prime number?
No. 21126 = 2 × 3 × 7 × 503, so it is divisible by 2.
What are the factors of 21126?
1, 2, 3, 6, 7, 14, 21, 42, 503, 1006, 1509, 3018, 3521, 7042, 10563, 21126.
What is 21126 in binary?
101001010000110 (hexadecimal 5286, octal 51206).
What is the square root of 21126?
About 145.3479.
Is 21126 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 21126?
It is a composite number with 16 divisors.