The number 21994
21994 is a composite number with 8 divisors. Its prime factorisation is 2 × 7 × 1571. Divisors (8): 1, 2, 7, 14, 1571, 3142, 10997, 21994.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21994 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21994 is composite. Its prime factorisation is
- 3
The divisors add up to 37728; without 21994 itself that is 15734, so 21994 is deficient (15734 is less than 21994). Euler's totient φ(21994) = 9420 numbers up to 21994 share no factor with it.
- 4
The digits of 21994 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 43 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21994 = 2 \times 7 \times 1571 \]
21994 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 37728 |
| Euler totient φ(n) | 9420 |
| Square | 483736036 |
| Cube | 10639290375784 |
| Square root | 148.303742 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.1994 × |
21994 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand nine hundred and ninety-four |
| Binary (base 2) | 101010111101010 |
| Octal (base 8) | 52752 |
| Hexadecimal (base 16) | 55EA |
| Base 3 | 1010011121 |
| As time | 21994 seconds = 6 h 6 min 34 s |
Is 21994 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21994 ÷ 2 = 10997) | 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 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21994 ÷ 7 = 3142) | 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 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 4) | 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 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21994 a prime number?
No. 21994 = 2 × 7 × 1571, so it is divisible by 2.
What are the factors of 21994?
1, 2, 7, 14, 1571, 3142, 10997, 21994.
What is 21994 in binary?
101010111101010 (hexadecimal 55EA, octal 52752).
What is the square root of 21994?
About 148.3037.
Is 21994 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 21994?
It is a composite number with 8 divisors.