The number 31820
31820 is a composite number with 24 divisors. Its prime factorisation is × 5 × 37 × 43. Divisors (24): 1, 2, 4, 5, 10, 20, 37, 43, 74, 86, 148, 172, 185, 215, 370, 430 … 31820.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31820 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31820 is composite. Its prime factorisation is
- 3
The divisors add up to 70224; without 31820 itself that is 38404, so 31820 is abundant (38404 is more than 31820). Euler's totient φ(31820) = 12096 numbers up to 31820 share no factor with it.
- 4
The digits of 31820 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
\[ 31820 = 2^{2} \times 5 \times 37 \times 43 \]31820 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 70224 |
| Euler totient φ(n) | 12096 |
| Square | 1012512400 |
| Cube | 32218144568000 |
| Square root | 178.381613 (= 2√7955) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.182 × |
31820 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and twenty |
| Binary (base 2) | 111110001001100 |
| Octal (base 8) | 76114 |
| Hexadecimal (base 16) | 7C4C |
| Base 3 | 1121122112 |
| As time | 31820 seconds = 8 h 50 min 20 s |
Is 31820 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31820 ÷ 2 = 15910) | 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 (31820 ÷ 4 = 7955) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31820 ÷ 5 = 6364) | 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 | No (remainder 4) | 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 (31820 ÷ 10 = 3182) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | 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 31820 a prime number?
No. 31820 = × 5 × 37 × 43, so it is divisible by 2.
What are the factors of 31820?
1, 2, 4, 5, 10, 20, 37, 43, 74, 86, 148, 172, 185, 215, 370, 430, 740, 860, 1591, 3182, 6364, 7955, 15910, 31820.
What is 31820 in binary?
111110001001100 (hexadecimal 7C4C, octal 76114).
What is the square root of 31820?
About 178.3816, exactly 2√7955.
Is 31820 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 31820?
It is a composite number with 24 divisors.