The number 21497
21497 is a composite number with 8 divisors. Its prime factorisation is 7 × 37 × 83. Divisors (8): 1, 7, 37, 83, 259, 581, 3071, 21497.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21497 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21497 is composite. Its prime factorisation is
- 3
The divisors add up to 25536; without 21497 itself that is 4039, so 21497 is deficient (4039 is less than 21497). Euler's totient φ(21497) = 17712 numbers up to 21497 share no factor with it.
- 4
The digits of 21497 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21497 = 7 \times 37 \times 83 \]
21497 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 25536 |
| Euler totient φ(n) | 17712 |
| Square | 462121009 |
| Cube | 9934215330473 |
| Square root | 146.618553 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1497 × |
21497 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and ninety-seven |
| Binary (base 2) | 101001111111001 |
| Octal (base 8) | 51771 |
| Hexadecimal (base 16) | 53F9 |
| Base 3 | 1002111012 |
| As time | 21497 seconds = 5 h 58 min 17 s |
Is 21497 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 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21497 ÷ 7 = 3071) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21497 a prime number?
No. 21497 = 7 × 37 × 83, so it is divisible by 7.
What are the factors of 21497?
1, 7, 37, 83, 259, 581, 3071, 21497.
What is 21497 in binary?
101001111111001 (hexadecimal 53F9, octal 51771).
What is the square root of 21497?
About 146.6186.
Is 21497 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 21497?
It is a composite number with 8 divisors.