The number 21750
21750 is a composite number with 32 divisors. Its prime factorisation is 2 × 3 × × 29. Divisors (32): 1, 2, 3, 5, 6, 10, 15, 25, 29, 30, 50, 58, 75, 87, 125, 145 … 21750.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21750: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 15.
- 2
21750 is composite. Its prime factorisation is
- 3
The divisors add up to 56160; without 21750 itself that is 34410, so 21750 is abundant (34410 is more than 21750). Euler's totient φ(21750) = 5600 numbers up to 21750 share no factor with it.
- 4
The digits of 21750 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 118 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21750 = 2 \times 3 \times 5^{3} \times 29 \]21750 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 56160 |
| Euler totient φ(n) | 5600 |
| Square | 473062500 |
| Cube | 10289109375000 |
| Square root | 147.478812 (= 5√870) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 118 |
| Scientific notation | 2.175 × |
21750 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and fifty |
| Binary (base 2) | 101010011110110 |
| Octal (base 8) | 52366 |
| Hexadecimal (base 16) | 54F6 |
| Base 3 | 1002211120 |
| As time | 21750 seconds = 6 h 2 min 30 s |
Is 21750 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21750 ÷ 2 = 10875) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21750 ÷ 3 = 7250) | 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 | Yes (21750 ÷ 5 = 4350) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21750 ÷ 6 = 3625) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21750 ÷ 10 = 2175) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21750 a prime number?
No. 21750 = 2 × 3 × × 29, so it is divisible by 2.
What are the factors of 21750?
1, 2, 3, 5, 6, 10, 15, 25, 29, 30, 50, 58, 75, 87, 125, 145, 150, 174, 250, 290, 375, 435, 725, 750, 870, 1450, 2175, 3625, 4350, 7250, 10875, 21750.
What is 21750 in binary?
101010011110110 (hexadecimal 54F6, octal 52366).
What is the square root of 21750?
About 147.4788, exactly 5√870.
Is 21750 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 21750?
21750 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 15.