The number 31640
31640 is a composite number with 32 divisors. Its prime factorisation is × 5 × 7 × 113. Divisors (32): 1, 2, 4, 5, 7, 8, 10, 14, 20, 28, 35, 40, 56, 70, 113, 140 … 31640.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31640: a Harshad number: divisible by its digit sum 14.
- 2
31640 is composite. Its prime factorisation is
- 3
The divisors add up to 82080; without 31640 itself that is 50440, so 31640 is abundant (50440 is more than 31640). Euler's totient φ(31640) = 10752 numbers up to 31640 share no factor with it.
- 4
The digits of 31640 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 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31640 = 2^{3} \times 5 \times 7 \times 113 \]31640 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 82080 |
| Euler totient φ(n) | 10752 |
| Square | 1001089600 |
| Cube | 31674474944000 |
| Square root | 177.876362 (= 2√7910) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.164 × |
31640 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand six hundred and forty |
| Binary (base 2) | 111101110011000 |
| Octal (base 8) | 75630 |
| Hexadecimal (base 16) | 7B98 |
| Base 3 | 1121101212 |
| As time | 31640 seconds = 8 h 47 min 20 s |
Is 31640 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31640 ÷ 2 = 15820) | 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 (31640 ÷ 4 = 7910) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31640 ÷ 5 = 6328) | 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 | Yes (31640 ÷ 7 = 4520) | 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 (31640 ÷ 8 = 3955) | 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 (31640 ÷ 10 = 3164) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | 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 31640 a prime number?
No. 31640 = × 5 × 7 × 113, so it is divisible by 2.
What are the factors of 31640?
1, 2, 4, 5, 7, 8, 10, 14, 20, 28, 35, 40, 56, 70, 113, 140, 226, 280, 452, 565, 791, 904, 1130, 1582, 2260, 3164, 3955, 4520, 6328, 7910, 15820, 31640.
What is 31640 in binary?
111101110011000 (hexadecimal 7B98, octal 75630).
What is the square root of 31640?
About 177.8764, exactly 2√7910.
Is 31640 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 31640?
31640 is a Harshad number: divisible by its digit sum 14.