The number 1640
1640 is a composite number with 16 divisors. Its prime factorisation is × 5 × 41. Divisors (16): 1, 2, 4, 5, 8, 10, 20, 40, 41, 82, 164, 205, 328, 410, 820, 1640.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
1640 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
1640 is composite. Its prime factorisation is
- 3
The divisors add up to 3780; without 1640 itself that is 2140, so 1640 is abundant (2140 is more than 1640). Euler's totient φ(1640) = 640 numbers up to 1640 share no factor with it.
- 4
The digits of 1640 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 29 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1640 = 2^{3} \times 5 \times 41 \]1640 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 3780 |
| Euler totient φ(n) | 640 |
| Square | 2689600 |
| Cube | 4410944000 |
| Square root | 40.496913 (= 2√410) |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 29 |
| Scientific notation | 1.64 × |
1640 in other forms
| Form | Value |
|---|---|
| In words | one thousand six hundred and forty |
| Roman numerals | MDCXL |
| Binary (base 2) | 11001101000 |
| Octal (base 8) | 3150 |
| Hexadecimal (base 16) | 668 |
| Base 3 | 2020202 |
| As time | 1640 seconds = 27 min 20 s |
Is 1640 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (1640 ÷ 2 = 820) | 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 (1640 ÷ 4 = 410) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (1640 ÷ 5 = 328) | 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 2) | 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 (1640 ÷ 8 = 205) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (1640 ÷ 10 = 164) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | 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 1640 a prime number?
No. 1640 = × 5 × 41, so it is divisible by 2.
What are the factors of 1640?
1, 2, 4, 5, 8, 10, 20, 40, 41, 82, 164, 205, 328, 410, 820, 1640.
What is 1640 in binary?
11001101000 (hexadecimal 668, octal 3150).
What is the square root of 1640?
About 40.4969, exactly 2√410.
What is 1640 in Roman numerals?
MDCXL.
Is 1640 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 1640?
It is a composite number with 16 divisors.