The number 8420
8420 is a composite number with 12 divisors. Its prime factorisation is × 5 × 421. Divisors (12): 1, 2, 4, 5, 10, 20, 421, 842, 1684, 2105, 4210, 8420.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
8420 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
8420 is composite. Its prime factorisation is
- 3
The divisors add up to 17724; without 8420 itself that is 9304, so 8420 is abundant (9304 is more than 8420). Euler's totient φ(8420) = 3360 numbers up to 8420 share no factor with it.
- 4
The digits of 8420 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 127 steps to reach 1.
LaTeX source of the formulas on this page
\[ 8420 = 2^{2} \times 5 \times 421 \]8420 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 17724 |
| Euler totient φ(n) | 3360 |
| Square | 70896400 |
| Cube | 596947688000 |
| Square root | 91.760558 (= 2√2105) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 127 |
| Scientific notation | 8.42 × |
8420 in other forms
| Form | Value |
|---|---|
| In words | eight thousand four hundred and twenty |
| Binary (base 2) | 10000011100100 |
| Octal (base 8) | 20344 |
| Hexadecimal (base 16) | 20E4 |
| Base 3 | 102112212 |
| As time | 8420 seconds = 2 h 20 min 20 s |
Is 8420 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (8420 ÷ 2 = 4210) | 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 (8420 ÷ 4 = 2105) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (8420 ÷ 5 = 1684) | 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 6) | 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 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (8420 ÷ 10 = 842) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 8420 a prime number?
No. 8420 = × 5 × 421, so it is divisible by 2.
What are the factors of 8420?
1, 2, 4, 5, 10, 20, 421, 842, 1684, 2105, 4210, 8420.
What is 8420 in binary?
10000011100100 (hexadecimal 20E4, octal 20344).
What is the square root of 8420?
About 91.7606, exactly 2√2105.
Is 8420 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 8420?
It is a composite number with 12 divisors.