The number 31215
31215 is a composite number with 8 divisors. Its prime factorisation is 3 × 5 × 2081. Divisors (8): 1, 3, 5, 15, 2081, 6243, 10405, 31215.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31215 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31215 is composite. Its prime factorisation is
- 3
The divisors add up to 49968; without 31215 itself that is 18753, so 31215 is deficient (18753 is less than 31215). Euler's totient φ(31215) = 16640 numbers up to 31215 share no factor with it.
- 4
The digits of 31215 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 209 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31215 = 3 \times 5 \times 2081 \]
31215 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 49968 |
| Euler totient φ(n) | 16640 |
| Square | 974376225 |
| Cube | 30415153863375 |
| Square root | 176.677673 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 209 |
| Scientific notation | 3.1215 × |
31215 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand two hundred and fifteen |
| Binary (base 2) | 111100111101111 |
| Octal (base 8) | 74757 |
| Hexadecimal (base 16) | 79EF |
| Base 3 | 1120211010 |
| As time | 31215 seconds = 8 h 40 min 15 s |
Is 31215 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31215 ÷ 3 = 10405) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31215 ÷ 5 = 6243) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 | No (remainder 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31215 a prime number?
No. 31215 = 3 × 5 × 2081, so it is divisible by 3.
What are the factors of 31215?
1, 3, 5, 15, 2081, 6243, 10405, 31215.
What is 31215 in binary?
111100111101111 (hexadecimal 79EF, octal 74757).
What is the square root of 31215?
About 176.6777.
Is 31215 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 31215?
It is a composite number with 8 divisors.