The number 31240
31240 is a composite number with 32 divisors. Its prime factorisation is × 5 × 11 × 71. Divisors (32): 1, 2, 4, 5, 8, 10, 11, 20, 22, 40, 44, 55, 71, 88, 110, 142 … 31240.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31240: a Harshad number: divisible by its digit sum 10.
- 2
31240 is composite. Its prime factorisation is
- 3
The divisors add up to 77760; without 31240 itself that is 46520, so 31240 is abundant (46520 is more than 31240). Euler's totient φ(31240) = 11200 numbers up to 31240 share no factor with it.
- 4
The digits of 31240 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 103 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31240 = 2^{3} \times 5 \times 11 \times 71 \]31240 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 77760 |
| Euler totient φ(n) | 11200 |
| Square | 975937600 |
| Cube | 30488290624000 |
| Square root | 176.748409 (= 2√7810) |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 103 |
| Scientific notation | 3.124 × |
31240 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand two hundred and forty |
| Binary (base 2) | 111101000001000 |
| Octal (base 8) | 75010 |
| Hexadecimal (base 16) | 7A08 |
| Base 3 | 1120212001 |
| As time | 31240 seconds = 8 h 40 min 40 s |
Is 31240 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31240 ÷ 2 = 15620) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (31240 ÷ 4 = 7810) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (31240 ÷ 5 = 6248) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | 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 (31240 ÷ 8 = 3905) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (31240 ÷ 10 = 3124) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (31240 ÷ 11 = 2840) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31240 a prime number?
No. 31240 = × 5 × 11 × 71, so it is divisible by 2.
What are the factors of 31240?
1, 2, 4, 5, 8, 10, 11, 20, 22, 40, 44, 55, 71, 88, 110, 142, 220, 284, 355, 440, 568, 710, 781, 1420, 1562, 2840, 3124, 3905, 6248, 7810, 15620, 31240.
What is 31240 in binary?
111101000001000 (hexadecimal 7A08, octal 75010).
What is the square root of 31240?
About 176.7484, exactly 2√7810.
Is 31240 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 31240?
31240 is a Harshad number: divisible by its digit sum 10.