The number 21880
21880 is a composite number with 16 divisors. Its prime factorisation is × 5 × 547. Divisors (16): 1, 2, 4, 5, 8, 10, 20, 40, 547, 1094, 2188, 2735, 4376, 5470, 10940, 21880.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21880: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21880 is composite. Its prime factorisation is
- 3
The divisors add up to 49320; without 21880 itself that is 27440, so 21880 is abundant (27440 is more than 21880). Euler's totient φ(21880) = 8736 numbers up to 21880 share no factor with it.
- 4
The digits of 21880 add up to 19, 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
\[ 21880 = 2^{3} \times 5 \times 547 \]21880 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 49320 |
| Euler totient φ(n) | 8736 |
| Square | 478734400 |
| Cube | 10474708672000 |
| Square root | 147.918897 (= 2√5470) |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.188 × |
21880 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and eighty |
| Binary (base 2) | 101010101111000 |
| Octal (base 8) | 52570 |
| Hexadecimal (base 16) | 5578 |
| Base 3 | 1010000101 |
| As time | 21880 seconds = 6 h 4 min 40 s |
Is 21880 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21880 ÷ 2 = 10940) | 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 (21880 ÷ 4 = 5470) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21880 ÷ 5 = 4376) | 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 5) | 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 | Yes (21880 ÷ 8 = 2735) | 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 (21880 ÷ 10 = 2188) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | 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 21880 a prime number?
No. 21880 = × 5 × 547, so it is divisible by 2.
What are the factors of 21880?
1, 2, 4, 5, 8, 10, 20, 40, 547, 1094, 2188, 2735, 4376, 5470, 10940, 21880.
What is 21880 in binary?
101010101111000 (hexadecimal 5578, octal 52570).
What is the square root of 21880?
About 147.9189, exactly 2√5470.
Is 21880 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 21880?
21880 is a happy number: repeatedly adding the squares of its digits reaches 1.