The number 21172
21172 is a composite number with 12 divisors. Its prime factorisation is × 67 × 79. Divisors (12): 1, 2, 4, 67, 79, 134, 158, 268, 316, 5293, 10586, 21172.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21172 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21172 is composite. Its prime factorisation is
- 3
The divisors add up to 38080; without 21172 itself that is 16908, so 21172 is deficient (16908 is less than 21172). Euler's totient φ(21172) = 10296 numbers up to 21172 share no factor with it.
- 4
The digits of 21172 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21172 = 2^{2} \times 67 \times 79 \]21172 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 38080 |
| Euler totient φ(n) | 10296 |
| Square | 448253584 |
| Cube | 9490424880448 |
| Square root | 145.506014 (= 2√5293) |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1172 × |
21172 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and seventy-two |
| Binary (base 2) | 101001010110100 |
| Octal (base 8) | 51264 |
| Hexadecimal (base 16) | 52B4 |
| Base 3 | 1002001011 |
| As time | 21172 seconds = 5 h 52 min 52 s |
Is 21172 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21172 ÷ 2 = 10586) | 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 | Yes (21172 ÷ 4 = 5293) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21172 a prime number?
No. 21172 = × 67 × 79, so it is divisible by 2.
What are the factors of 21172?
1, 2, 4, 67, 79, 134, 158, 268, 316, 5293, 10586, 21172.
What is 21172 in binary?
101001010110100 (hexadecimal 52B4, octal 51264).
What is the square root of 21172?
About 145.5060, exactly 2√5293.
Is 21172 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 21172?
It is a composite number with 12 divisors.