The number 21490
21490 is a composite number with 16 divisors. Its prime factorisation is 2 × 5 × 7 × 307. Divisors (16): 1, 2, 5, 7, 10, 14, 35, 70, 307, 614, 1535, 2149, 3070, 4298, 10745, 21490.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21490 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21490 is composite. Its prime factorisation is
- 3
The divisors add up to 44352; without 21490 itself that is 22862, so 21490 is abundant (22862 is more than 21490). Euler's totient φ(21490) = 7344 numbers up to 21490 share no factor with it.
- 4
The digits of 21490 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21490 = 2 \times 5 \times 7 \times 307 \]
21490 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 44352 |
| Euler totient φ(n) | 7344 |
| Square | 461820100 |
| Cube | 9924513949000 |
| Square root | 146.594679 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.149 × |
21490 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and ninety |
| Binary (base 2) | 101001111110010 |
| Octal (base 8) | 51762 |
| Hexadecimal (base 16) | 53F2 |
| Base 3 | 1002110221 |
| As time | 21490 seconds = 5 h 58 min 10 s |
Is 21490 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21490 ÷ 2 = 10745) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21490 ÷ 5 = 4298) | 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 | Yes (21490 ÷ 7 = 3070) | 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 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21490 ÷ 10 = 2149) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21490 a prime number?
No. 21490 = 2 × 5 × 7 × 307, so it is divisible by 2.
What are the factors of 21490?
1, 2, 5, 7, 10, 14, 35, 70, 307, 614, 1535, 2149, 3070, 4298, 10745, 21490.
What is 21490 in binary?
101001111110010 (hexadecimal 53F2, octal 51762).
What is the square root of 21490?
About 146.5947.
Is 21490 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 21490?
It is a composite number with 16 divisors.