The number 21938
21938 is a composite number with 8 divisors. Its prime factorisation is 2 × 7 × 1567. Divisors (8): 1, 2, 7, 14, 1567, 3134, 10969, 21938.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21938 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21938 is composite. Its prime factorisation is
- 3
The divisors add up to 37632; without 21938 itself that is 15694, so 21938 is deficient (15694 is less than 21938). Euler's totient φ(21938) = 9396 numbers up to 21938 share no factor with it.
- 4
The digits of 21938 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 43 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21938 = 2 \times 7 \times 1567 \]
21938 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 37632 |
| Euler totient φ(n) | 9396 |
| Square | 481275844 |
| Cube | 10558229465672 |
| Square root | 148.114820 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.1938 × |
21938 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand nine hundred and thirty-eight |
| Binary (base 2) | 101010110110010 |
| Octal (base 8) | 52662 |
| Hexadecimal (base 16) | 55B2 |
| Base 3 | 1010002112 |
| As time | 21938 seconds = 6 h 5 min 38 s |
Is 21938 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21938 ÷ 2 = 10969) | 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 2) | 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 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21938 ÷ 7 = 3134) | 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 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21938 a prime number?
No. 21938 = 2 × 7 × 1567, so it is divisible by 2.
What are the factors of 21938?
1, 2, 7, 14, 1567, 3134, 10969, 21938.
What is 21938 in binary?
101010110110010 (hexadecimal 55B2, octal 52662).
What is the square root of 21938?
About 148.1148.
Is 21938 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 21938?
It is a composite number with 8 divisors.