The number 21331
21331 is a composite number with 4 divisors. Its prime factorisation is 83 × 257. Divisors (4): 1, 83, 257, 21331.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21331: a semiprime: 83 × 257, the product of two primes.
- 2
21331 is composite. Its prime factorisation is
- 3
The divisors add up to 21672; without 21331 itself that is 341, so 21331 is deficient (341 is less than 21331). Euler's totient φ(21331) = 20992 numbers up to 21331 share no factor with it.
- 4
The digits of 21331 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 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21331 = 83 \times 257 \]
21331 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 21672 |
| Euler totient φ(n) | 20992 |
| Square | 455011561 |
| Cube | 9705851607691 |
| Square root | 146.051361 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1331 × |
21331 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and thirty-one |
| Binary (base 2) | 101001101010011 |
| Octal (base 8) | 51523 |
| Hexadecimal (base 16) | 5353 |
| Base 3 | 1002021001 |
| As time | 21331 seconds = 5 h 55 min 31 s |
Is 21331 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 3) | 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 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 3) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21331 a prime number?
No. 21331 = 83 × 257, so it is divisible by 83.
What are the factors of 21331?
1, 83, 257, 21331.
What is 21331 in binary?
101001101010011 (hexadecimal 5353, octal 51523).
What is the square root of 21331?
About 146.0514.
Is 21331 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21331?
21331 is a semiprime: 83 × 257, the product of two primes.