The number 21700
21700 is a composite number with 36 divisors. Its prime factorisation is × × 7 × 31. Divisors (36): 1, 2, 4, 5, 7, 10, 14, 20, 25, 28, 31, 35, 50, 62, 70, 100 … 21700.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21700: a Harshad number: divisible by its digit sum 10.
- 2
21700 is composite. Its prime factorisation is
- 3
The divisors add up to 55552; without 21700 itself that is 33852, so 21700 is abundant (33852 is more than 21700). Euler's totient φ(21700) = 7200 numbers up to 21700 share no factor with it.
- 4
The digits of 21700 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 162 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21700 = 2^{2} \times 5^{2} \times 7 \times 31 \]21700 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 36 |
| Sum of divisors | 55552 |
| Euler totient φ(n) | 7200 |
| Square | 470890000 |
| Cube | 10218313000000 |
| Square root | 147.309199 (= 10√217) |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.17 × |
21700 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred |
| Binary (base 2) | 101010011000100 |
| Octal (base 8) | 52304 |
| Hexadecimal (base 16) | 54C4 |
| Base 3 | 1002202201 |
| As time | 21700 seconds = 6 h 1 min 40 s |
Is 21700 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21700 ÷ 2 = 10850) | 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 (21700 ÷ 4 = 5425) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21700 ÷ 5 = 4340) | 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 (21700 ÷ 7 = 3100) | 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 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21700 ÷ 10 = 2170) | 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 21700 a prime number?
No. 21700 = × × 7 × 31, so it is divisible by 2.
What are the factors of 21700?
1, 2, 4, 5, 7, 10, 14, 20, 25, 28, 31, 35, 50, 62, 70, 100, 124, 140, 155, 175, 217, 310, 350, 434, 620, 700, 775, 868, 1085, 1550, 2170, 3100, 4340, 5425, 10850, 21700.
What is 21700 in binary?
101010011000100 (hexadecimal 54C4, octal 52304).
What is the square root of 21700?
About 147.3092, exactly 10√217.
Is 21700 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21700?
21700 is a Harshad number: divisible by its digit sum 10.