The number 20420
20420 is a composite number with 12 divisors. Its prime factorisation is × 5 × 1021. Divisors (12): 1, 2, 4, 5, 10, 20, 1021, 2042, 4084, 5105, 10210, 20420.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
20420 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
20420 is composite. Its prime factorisation is
- 3
The divisors add up to 42924; without 20420 itself that is 22504, so 20420 is abundant (22504 is more than 20420). Euler's totient φ(20420) = 8160 numbers up to 20420 share no factor with it.
- 4
The digits of 20420 add up to 8, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20420 = 2^{2} \times 5 \times 1021 \]20420 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 42924 |
| Euler totient φ(n) | 8160 |
| Square | 416976400 |
| Cube | 8514658088000 |
| Square root | 142.898565 (= 2√5105) |
| Digit sum / digital root | 8 / 8 |
| Collatz steps to 1 | 61 |
| Scientific notation | 2.042 × |
20420 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand four hundred and twenty |
| Binary (base 2) | 100111111000100 |
| Octal (base 8) | 47704 |
| Hexadecimal (base 16) | 4FC4 |
| Base 3 | 1001000022 |
| As time | 20420 seconds = 5 h 40 min 20 s |
Is 20420 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (20420 ÷ 2 = 10210) | 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 (20420 ÷ 4 = 5105) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (20420 ÷ 5 = 4084) | 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 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (20420 ÷ 10 = 2042) | 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 20420 a prime number?
No. 20420 = × 5 × 1021, so it is divisible by 2.
What are the factors of 20420?
1, 2, 4, 5, 10, 20, 1021, 2042, 4084, 5105, 10210, 20420.
What is 20420 in binary?
100111111000100 (hexadecimal 4FC4, octal 47704).
What is the square root of 20420?
About 142.8986, exactly 2√5105.
Is 20420 divisible by 3?
No. Its digits add up to 8, which is not a multiple of 3.
What is special about the number 20420?
It is a composite number with 12 divisors.