The number 21949
21949 is a composite number with 4 divisors. Its prime factorisation is 47 × 467. Divisors (4): 1, 47, 467, 21949.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21949: a semiprime: 47 × 467, the product of two primes.
- 2
21949 is composite. Its prime factorisation is
- 3
The divisors add up to 22464; without 21949 itself that is 515, so 21949 is deficient (515 is less than 21949). Euler's totient φ(21949) = 21436 numbers up to 21949 share no factor with it.
- 4
The digits of 21949 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 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21949 = 47 \times 467 \]
21949 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22464 |
| Euler totient φ(n) | 21436 |
| Square | 481758601 |
| Cube | 10574119533349 |
| Square root | 148.151949 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1949 × |
21949 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand nine hundred and forty-nine |
| Binary (base 2) | 101010110111101 |
| Octal (base 8) | 52675 |
| Hexadecimal (base 16) | 55BD |
| Base 3 | 1010002221 |
| As time | 21949 seconds = 6 h 5 min 49 s |
Is 21949 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 4) | 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 5) | 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 9) | 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 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21949 a prime number?
No. 21949 = 47 × 467, so it is divisible by 47.
What are the factors of 21949?
1, 47, 467, 21949.
What is 21949 in binary?
101010110111101 (hexadecimal 55BD, octal 52675).
What is the square root of 21949?
About 148.1519.
Is 21949 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 21949?
21949 is a semiprime: 47 × 467, the product of two primes.