The number 31209
31209 is a composite number with 8 divisors. Its prime factorisation is 3 × 101 × 103. Divisors (8): 1, 3, 101, 103, 303, 309, 10403, 31209.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31209 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31209 is composite. Its prime factorisation is
- 3
The divisors add up to 42432; without 31209 itself that is 11223, so 31209 is deficient (11223 is less than 31209). Euler's totient φ(31209) = 20400 numbers up to 31209 share no factor with it.
- 4
The digits of 31209 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 178 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31209 = 3 \times 101 \times 103 \]
31209 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 42432 |
| Euler totient φ(n) | 20400 |
| Square | 974001681 |
| Cube | 30397618462329 |
| Square root | 176.660692 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 178 |
| Scientific notation | 3.1209 × |
31209 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand two hundred and nine |
| Binary (base 2) | 111100111101001 |
| Octal (base 8) | 74751 |
| Hexadecimal (base 16) | 79E9 |
| Base 3 | 1120210220 |
| As time | 31209 seconds = 8 h 40 min 9 s |
Is 31209 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 | Yes (31209 ÷ 3 = 10403) | 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 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 1) | 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 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31209 a prime number?
No. 31209 = 3 × 101 × 103, so it is divisible by 3.
What are the factors of 31209?
1, 3, 101, 103, 303, 309, 10403, 31209.
What is 31209 in binary?
111100111101001 (hexadecimal 79E9, octal 74751).
What is the square root of 31209?
About 176.6607.
Is 31209 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 31209?
It is a composite number with 8 divisors.