The number 31428
31428 is a composite number with 30 divisors. Its prime factorisation is × × 97. Divisors (30): 1, 2, 3, 4, 6, 9, 12, 18, 27, 36, 54, 81, 97, 108, 162, 194 … 31428.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31428: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 18.
- 2
31428 is composite. Its prime factorisation is
- 3
The divisors add up to 83006; without 31428 itself that is 51578, so 31428 is abundant (51578 is more than 31428). Euler's totient φ(31428) = 10368 numbers up to 31428 share no factor with it.
- 4
The digits of 31428 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 103 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31428 = 2^{2} \times 3^{4} \times 97 \]31428 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 30 |
| Sum of divisors | 83006 |
| Euler totient φ(n) | 10368 |
| Square | 987719184 |
| Cube | 31042038514752 |
| Square root | 177.279440 (= 18√97) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 103 |
| Scientific notation | 3.1428 × |
31428 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand four hundred and twenty-eight |
| Binary (base 2) | 111101011000100 |
| Octal (base 8) | 75304 |
| Hexadecimal (base 16) | 7AC4 |
| Base 3 | 1121010000 |
| As time | 31428 seconds = 8 h 43 min 48 s |
Is 31428 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31428 ÷ 2 = 15714) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (31428 ÷ 3 = 10476) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (31428 ÷ 4 = 7857) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (31428 ÷ 6 = 5238) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (31428 ÷ 9 = 3492) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | 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 | Yes (31428 ÷ 12 = 2619) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31428 a prime number?
No. 31428 = × × 97, so it is divisible by 2.
What are the factors of 31428?
1, 2, 3, 4, 6, 9, 12, 18, 27, 36, 54, 81, 97, 108, 162, 194, 291, 324, 388, 582, 873, 1164, 1746, 2619, 3492, 5238, 7857, 10476, 15714, 31428.
What is 31428 in binary?
111101011000100 (hexadecimal 7AC4, octal 75304).
What is the square root of 31428?
About 177.2794, exactly 18√97.
Is 31428 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 31428?
31428 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 18.