The number 31478
31478 is a composite number with 4 divisors. Its prime factorisation is 2 × 15739. Divisors (4): 1, 2, 15739, 31478.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31478: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 15739, the product of two primes.
- 2
31478 is composite. Its prime factorisation is
- 3
The divisors add up to 47220; without 31478 itself that is 15742, so 31478 is deficient (15742 is less than 31478). Euler's totient φ(31478) = 15738 numbers up to 31478 share no factor with it.
- 4
The digits of 31478 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31478 = 2 \times 15739 \]
31478 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 47220 |
| Euler totient φ(n) | 15738 |
| Square | 990864484 |
| Cube | 31190432227352 |
| Square root | 177.420405 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1478 × |
31478 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand four hundred and seventy-eight |
| Binary (base 2) | 111101011110110 |
| Octal (base 8) | 75366 |
| Hexadecimal (base 16) | 7AF6 |
| Base 3 | 1121011212 |
| As time | 31478 seconds = 8 h 44 min 38 s |
Is 31478 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (31478 ÷ 2 = 15739) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | 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 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | 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 | No (remainder 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31478 a prime number?
No. 31478 = 2 × 15739, so it is divisible by 2.
What are the factors of 31478?
1, 2, 15739, 31478.
What is 31478 in binary?
111101011110110 (hexadecimal 7AF6, octal 75366).
What is the square root of 31478?
About 177.4204.
Is 31478 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 31478?
31478 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 15739, the product of two primes.