The number 31421
31421 is a composite number with 4 divisors. Its prime factorisation is 13 × 2417. Divisors (4): 1, 13, 2417, 31421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31421: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 13 × 2417, the product of two primes.
- 2
31421 is composite. Its prime factorisation is
- 3
The divisors add up to 33852; without 31421 itself that is 2431, so 31421 is deficient (2431 is less than 31421). Euler's totient φ(31421) = 28992 numbers up to 31421 share no factor with it.
- 4
The digits of 31421 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 85 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31421 = 13 \times 2417 \]
31421 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 33852 |
| Euler totient φ(n) | 28992 |
| Square | 987279241 |
| Cube | 31021301031461 |
| Square root | 177.259696 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.1421 × |
31421 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand four hundred and twenty-one |
| Binary (base 2) | 111101010111101 |
| Octal (base 8) | 75275 |
| Hexadecimal (base 16) | 7ABD |
| Base 3 | 1121002202 |
| As time | 31421 seconds = 8 h 43 min 41 s |
Is 31421 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31421 a prime number?
No. 31421 = 13 × 2417, so it is divisible by 13.
What are the factors of 31421?
1, 13, 2417, 31421.
What is 31421 in binary?
111101010111101 (hexadecimal 7ABD, octal 75275).
What is the square root of 31421?
About 177.2597.
Is 31421 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 31421?
31421 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 13 × 2417, the product of two primes.