The number 21983
21983 is a composite number with 8 divisors. Its prime factorisation is 13 × 19 × 89. Divisors (8): 1, 13, 19, 89, 247, 1157, 1691, 21983.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21983 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21983 is composite. Its prime factorisation is
- 3
The divisors add up to 25200; without 21983 itself that is 3217, so 21983 is deficient (3217 is less than 21983). Euler's totient φ(21983) = 19008 numbers up to 21983 share no factor with it.
- 4
The digits of 21983 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 100 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21983 = 13 \times 19 \times 89 \]
21983 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 25200 |
| Euler totient φ(n) | 19008 |
| Square | 483252289 |
| Cube | 10623335069087 |
| Square root | 148.266652 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 100 |
| Scientific notation | 2.1983 × |
21983 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand nine hundred and eighty-three |
| Binary (base 2) | 101010111011111 |
| Octal (base 8) | 52737 |
| Hexadecimal (base 16) | 55DF |
| Base 3 | 1010011012 |
| As time | 21983 seconds = 6 h 6 min 23 s |
Is 21983 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | 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 | No (remainder 3) | 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 7) | 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 3) | 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 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21983 a prime number?
No. 21983 = 13 × 19 × 89, so it is divisible by 13.
What are the factors of 21983?
1, 13, 19, 89, 247, 1157, 1691, 21983.
What is 21983 in binary?
101010111011111 (hexadecimal 55DF, octal 52737).
What is the square root of 21983?
About 148.2667.
Is 21983 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 21983?
It is a composite number with 8 divisors.