The number 31890
31890 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 5 × 1063. Divisors (16): 1, 2, 3, 5, 6, 10, 15, 30, 1063, 2126, 3189, 5315, 6378, 10630, 15945, 31890.
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How to work it out
- 1
31890 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31890 is composite. Its prime factorisation is
- 3
The divisors add up to 76608; without 31890 itself that is 44718, so 31890 is abundant (44718 is more than 31890). Euler's totient φ(31890) = 8496 numbers up to 31890 share no factor with it.
- 4
The digits of 31890 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 59 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31890 = 2 \times 3 \times 5 \times 1063 \]
31890 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 76608 |
| Euler totient φ(n) | 8496 |
| Square | 1016972100 |
| Cube | 32431240269000 |
| Square root | 178.577714 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 59 |
| Scientific notation | 3.189 × |
31890 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and ninety |
| Binary (base 2) | 111110010010010 |
| Octal (base 8) | 76222 |
| Hexadecimal (base 16) | 7C92 |
| Base 3 | 1121202010 |
| As time | 31890 seconds = 8 h 51 min 30 s |
Is 31890 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31890 ÷ 2 = 15945) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31890 ÷ 3 = 10630) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31890 ÷ 5 = 6378) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (31890 ÷ 6 = 5315) | 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 2) | 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 | Yes (31890 ÷ 10 = 3189) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31890 a prime number?
No. 31890 = 2 × 3 × 5 × 1063, so it is divisible by 2.
What are the factors of 31890?
1, 2, 3, 5, 6, 10, 15, 30, 1063, 2126, 3189, 5315, 6378, 10630, 15945, 31890.
What is 31890 in binary?
111110010010010 (hexadecimal 7C92, octal 76222).
What is the square root of 31890?
About 178.5777.
Is 31890 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 31890?
It is a composite number with 16 divisors.