The number 31520
31520 is a composite number with 24 divisors. Its prime factorisation is × 5 × 197. Divisors (24): 1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 80, 160, 197, 394, 788, 985 … 31520.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31520 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31520 is composite. Its prime factorisation is
- 3
The divisors add up to 74844; without 31520 itself that is 43324, so 31520 is abundant (43324 is more than 31520). Euler's totient φ(31520) = 12544 numbers up to 31520 share no factor with it.
- 4
The digits of 31520 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 28 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31520 = 2^{5} \times 5 \times 197 \]31520 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 74844 |
| Euler totient φ(n) | 12544 |
| Square | 993510400 |
| Cube | 31315447808000 |
| Square root | 177.538728 (= 4√1970) |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 28 |
| Scientific notation | 3.152 × |
31520 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand five hundred and twenty |
| Binary (base 2) | 111101100100000 |
| Octal (base 8) | 75440 |
| Hexadecimal (base 16) | 7B20 |
| Base 3 | 1121020102 |
| As time | 31520 seconds = 8 h 45 min 20 s |
Is 31520 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31520 ÷ 2 = 15760) | 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 (31520 ÷ 4 = 7880) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31520 ÷ 5 = 6304) | 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 6) | 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 (31520 ÷ 8 = 3940) | 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 (31520 ÷ 10 = 3152) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 31520 a prime number?
No. 31520 = × 5 × 197, so it is divisible by 2.
What are the factors of 31520?
1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 80, 160, 197, 394, 788, 985, 1576, 1970, 3152, 3940, 6304, 7880, 15760, 31520.
What is 31520 in binary?
111101100100000 (hexadecimal 7B20, octal 75440).
What is the square root of 31520?
About 177.5387, exactly 4√1970.
Is 31520 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 31520?
It is a composite number with 24 divisors.