The number 21697
21697 is a composite number with 4 divisors. Its prime factorisation is 13 × 1669. Divisors (4): 1, 13, 1669, 21697.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21697: a semiprime: 13 × 1669, the product of two primes.
- 2
21697 is composite. Its prime factorisation is
- 3
The divisors add up to 23380; without 21697 itself that is 1683, so 21697 is deficient (1683 is less than 21697). Euler's totient φ(21697) = 20016 numbers up to 21697 share no factor with it.
- 4
The digits of 21697 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 162 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21697 = 13 \times 1669 \]
21697 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 23380 |
| Euler totient φ(n) | 20016 |
| Square | 470759809 |
| Cube | 10214075575873 |
| Square root | 147.299016 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.1697 × |
21697 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand six hundred and ninety-seven |
| Binary (base 2) | 101010011000001 |
| Octal (base 8) | 52301 |
| Hexadecimal (base 16) | 54C1 |
| Base 3 | 1002202121 |
| As time | 21697 seconds = 6 h 1 min 37 s |
Is 21697 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 1) | 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 1) | 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 1) | 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 | No (remainder 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21697 a prime number?
No. 21697 = 13 × 1669, so it is divisible by 13.
What are the factors of 21697?
1, 13, 1669, 21697.
What is 21697 in binary?
101010011000001 (hexadecimal 54C1, octal 52301).
What is the square root of 21697?
About 147.2990.
Is 21697 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 21697?
21697 is a semiprime: 13 × 1669, the product of two primes.