The number 6420
6420 is a composite number with 24 divisors. Its prime factorisation is × 3 × 5 × 107. Divisors (24): 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60, 107, 214, 321, 428 … 6420.
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How to work it out
- 1
What is special about 6420: a Harshad number: divisible by its digit sum 12.
- 2
6420 is composite. Its prime factorisation is
- 3
The divisors add up to 18144; without 6420 itself that is 11724, so 6420 is abundant (11724 is more than 6420). Euler's totient φ(6420) = 1696 numbers up to 6420 share no factor with it.
- 4
The digits of 6420 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 23 steps to reach 1.
LaTeX source of the formulas on this page
\[ 6420 = 2^{2} \times 3 \times 5 \times 107 \]6420 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 18144 |
| Euler totient φ(n) | 1696 |
| Square | 41216400 |
| Cube | 264609288000 |
| Square root | 80.124902 (= 2√1605) |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 23 |
| Scientific notation | 6.42 × |
6420 in other forms
| Form | Value |
|---|---|
| In words | six thousand four hundred and twenty |
| Binary (base 2) | 1100100010100 |
| Octal (base 8) | 14424 |
| Hexadecimal (base 16) | 1914 |
| Base 3 | 22210210 |
| As time | 6420 seconds = 1 h 47 min 0 s |
Is 6420 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (6420 ÷ 2 = 3210) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (6420 ÷ 3 = 2140) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (6420 ÷ 4 = 1605) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (6420 ÷ 5 = 1284) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (6420 ÷ 6 = 1070) | 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 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (6420 ÷ 10 = 642) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (6420 ÷ 12 = 535) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 6420 a prime number?
No. 6420 = × 3 × 5 × 107, so it is divisible by 2.
What are the factors of 6420?
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60, 107, 214, 321, 428, 535, 642, 1070, 1284, 1605, 2140, 3210, 6420.
What is 6420 in binary?
1100100010100 (hexadecimal 1914, octal 14424).
What is the square root of 6420?
About 80.1249, exactly 2√1605.
Is 6420 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 6420?
6420 is a Harshad number: divisible by its digit sum 12.