The number 21080
21080 is a composite number with 32 divisors. Its prime factorisation is × 5 × 17 × 31. Divisors (32): 1, 2, 4, 5, 8, 10, 17, 20, 31, 34, 40, 62, 68, 85, 124, 136 … 21080.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21080 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21080 is composite. Its prime factorisation is
- 3
The divisors add up to 51840; without 21080 itself that is 30760, so 21080 is abundant (30760 is more than 21080). Euler's totient φ(21080) = 7680 numbers up to 21080 share no factor with it.
- 4
The digits of 21080 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21080 = 2^{3} \times 5 \times 17 \times 31 \]21080 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 51840 |
| Euler totient φ(n) | 7680 |
| Square | 444366400 |
| Cube | 9367243712000 |
| Square root | 145.189531 (= 2√5270) |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.108 × |
21080 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and eighty |
| Binary (base 2) | 101001001011000 |
| Octal (base 8) | 51130 |
| Hexadecimal (base 16) | 5258 |
| Base 3 | 1001220202 |
| As time | 21080 seconds = 5 h 51 min 20 s |
Is 21080 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21080 ÷ 2 = 10540) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21080 ÷ 4 = 5270) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21080 ÷ 5 = 4216) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 (21080 ÷ 8 = 2635) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21080 ÷ 10 = 2108) | 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 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21080 a prime number?
No. 21080 = × 5 × 17 × 31, so it is divisible by 2.
What are the factors of 21080?
1, 2, 4, 5, 8, 10, 17, 20, 31, 34, 40, 62, 68, 85, 124, 136, 155, 170, 248, 310, 340, 527, 620, 680, 1054, 1240, 2108, 2635, 4216, 5270, 10540, 21080.
What is 21080 in binary?
101001001011000 (hexadecimal 5258, octal 51130).
What is the square root of 21080?
About 145.1895, exactly 2√5270.
Is 21080 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 21080?
It is a composite number with 32 divisors.