The number 20440
20440 is a composite number with 32 divisors. Its prime factorisation is × 5 × 7 × 73. Divisors (32): 1, 2, 4, 5, 7, 8, 10, 14, 20, 28, 35, 40, 56, 70, 73, 140 … 20440.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20440: a Harshad number: divisible by its digit sum 10.
- 2
20440 is composite. Its prime factorisation is
- 3
The divisors add up to 53280; without 20440 itself that is 32840, so 20440 is abundant (32840 is more than 20440). Euler's totient φ(20440) = 6912 numbers up to 20440 share no factor with it.
- 4
The digits of 20440 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 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20440 = 2^{3} \times 5 \times 7 \times 73 \]20440 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 53280 |
| Euler totient φ(n) | 6912 |
| Square | 417793600 |
| Cube | 8539701184000 |
| Square root | 142.968528 (= 2√5110) |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 61 |
| Scientific notation | 2.044 × |
20440 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand four hundred and forty |
| Binary (base 2) | 100111111011000 |
| Octal (base 8) | 47730 |
| Hexadecimal (base 16) | 4FD8 |
| Base 3 | 1001001001 |
| As time | 20440 seconds = 5 h 40 min 40 s |
Is 20440 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (20440 ÷ 2 = 10220) | 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 (20440 ÷ 4 = 5110) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (20440 ÷ 5 = 4088) | 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 (20440 ÷ 7 = 2920) | 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 (20440 ÷ 8 = 2555) | 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 (20440 ÷ 10 = 2044) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | 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 20440 a prime number?
No. 20440 = × 5 × 7 × 73, so it is divisible by 2.
What are the factors of 20440?
1, 2, 4, 5, 7, 8, 10, 14, 20, 28, 35, 40, 56, 70, 73, 140, 146, 280, 292, 365, 511, 584, 730, 1022, 1460, 2044, 2555, 2920, 4088, 5110, 10220, 20440.
What is 20440 in binary?
100111111011000 (hexadecimal 4FD8, octal 47730).
What is the square root of 20440?
About 142.9685, exactly 2√5110.
Is 20440 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 20440?
20440 is a Harshad number: divisible by its digit sum 10.