The number 6640
6640 is a composite number with 20 divisors. Its prime factorisation is × 5 × 83. Divisors (20): 1, 2, 4, 5, 8, 10, 16, 20, 40, 80, 83, 166, 332, 415, 664, 830 … 6640.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 6640: a Harshad number: divisible by its digit sum 16.
- 2
6640 is composite. Its prime factorisation is
- 3
The divisors add up to 15624; without 6640 itself that is 8984, so 6640 is abundant (8984 is more than 6640). Euler's totient φ(6640) = 2624 numbers up to 6640 share no factor with it.
- 4
The digits of 6640 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 137 steps to reach 1.
LaTeX source of the formulas on this page
\[ 6640 = 2^{4} \times 5 \times 83 \]6640 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 15624 |
| Euler totient φ(n) | 2624 |
| Square | 44089600 |
| Cube | 292754944000 |
| Square root | 81.486195 (= 4√415) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 137 |
| Scientific notation | 6.64 × |
6640 in other forms
| Form | Value |
|---|---|
| In words | six thousand six hundred and forty |
| Binary (base 2) | 1100111110000 |
| Octal (base 8) | 14760 |
| Hexadecimal (base 16) | 19F0 |
| Base 3 | 100002221 |
| As time | 6640 seconds = 1 h 50 min 40 s |
Is 6640 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (6640 ÷ 2 = 3320) | 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 (6640 ÷ 4 = 1660) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (6640 ÷ 5 = 1328) | 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 | No (remainder 4) | 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 (6640 ÷ 8 = 830) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (6640 ÷ 10 = 664) | 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 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 6640 a prime number?
No. 6640 = × 5 × 83, so it is divisible by 2.
What are the factors of 6640?
1, 2, 4, 5, 8, 10, 16, 20, 40, 80, 83, 166, 332, 415, 664, 830, 1328, 1660, 3320, 6640.
What is 6640 in binary?
1100111110000 (hexadecimal 19F0, octal 14760).
What is the square root of 6640?
About 81.4862, exactly 4√415.
Is 6640 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 6640?
6640 is a Harshad number: divisible by its digit sum 16.