The number 31290
31290 is a composite number with 32 divisors. Its prime factorisation is 2 × 3 × 5 × 7 × 149. Divisors (32): 1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70, 105, 149 … 31290.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31290: a Harshad number: divisible by its digit sum 15.
- 2
31290 is composite. Its prime factorisation is
- 3
The divisors add up to 86400; without 31290 itself that is 55110, so 31290 is abundant (55110 is more than 31290). Euler's totient φ(31290) = 7104 numbers up to 31290 share no factor with it.
- 4
The digits of 31290 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 85 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31290 = 2 \times 3 \times 5 \times 7 \times 149 \]
31290 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 86400 |
| Euler totient φ(n) | 7104 |
| Square | 979064100 |
| Cube | 30634915689000 |
| Square root | 176.889796 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.129 × |
31290 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand two hundred and ninety |
| Binary (base 2) | 111101000111010 |
| Octal (base 8) | 75072 |
| Hexadecimal (base 16) | 7A3A |
| Base 3 | 1120220220 |
| As time | 31290 seconds = 8 h 41 min 30 s |
Is 31290 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31290 ÷ 2 = 15645) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31290 ÷ 3 = 10430) | 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 (31290 ÷ 5 = 6258) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (31290 ÷ 6 = 5215) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (31290 ÷ 7 = 4470) | 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 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (31290 ÷ 10 = 3129) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | 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 31290 a prime number?
No. 31290 = 2 × 3 × 5 × 7 × 149, so it is divisible by 2.
What are the factors of 31290?
1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70, 105, 149, 210, 298, 447, 745, 894, 1043, 1490, 2086, 2235, 3129, 4470, 5215, 6258, 10430, 15645, 31290.
What is 31290 in binary?
111101000111010 (hexadecimal 7A3A, octal 75072).
What is the square root of 31290?
About 176.8898.
Is 31290 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 31290?
31290 is a Harshad number: divisible by its digit sum 15.