The number 40640
40640 is a composite number with 28 divisors. Its prime factorisation is × 5 × 127. Divisors (28): 1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 127, 160, 254, 320 … 40640.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 40640: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
40640 is composite. Its prime factorisation is
- 3
The divisors add up to 97536; without 40640 itself that is 56896, so 40640 is abundant (56896 is more than 40640). Euler's totient φ(40640) = 16128 numbers up to 40640 share no factor with it.
- 4
The digits of 40640 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 36 steps to reach 1.
LaTeX source of the formulas on this page
\[ 40640 = 2^{6} \times 5 \times 127 \]40640 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 28 |
| Sum of divisors | 97536 |
| Euler totient φ(n) | 16128 |
| Square | 1651609600 |
| Cube | 67121414144000 |
| Square root | 201.593651 (= 8√635) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 36 |
| Scientific notation | 4.064 × |
40640 in other forms
| Form | Value |
|---|---|
| In words | forty thousand six hundred and forty |
| Binary (base 2) | 1001111011000000 |
| Octal (base 8) | 117300 |
| Hexadecimal (base 16) | 9EC0 |
| Base 3 | 2001202012 |
| As time | 40640 seconds = 11 h 17 min 20 s |
Is 40640 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (40640 ÷ 2 = 20320) | 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 (40640 ÷ 4 = 10160) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (40640 ÷ 5 = 8128) | 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 5) | 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 (40640 ÷ 8 = 5080) | 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 (40640 ÷ 10 = 4064) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | 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 40640 a prime number?
No. 40640 = × 5 × 127, so it is divisible by 2.
What are the factors of 40640?
1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 127, 160, 254, 320, 508, 635, 1016, 1270, 2032, 2540, 4064, 5080, 8128, 10160, 20320, 40640.
What is 40640 in binary?
1001111011000000 (hexadecimal 9EC0, octal 117300).
What is the square root of 40640?
About 201.5937, exactly 8√635.
Is 40640 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 40640?
40640 is a happy number: repeatedly adding the squares of its digits reaches 1.