The number 321
321 is a composite number with 4 divisors. Its prime factorisation is 3 × 107. Divisors (4): 1, 3, 107, 321.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 321: a semiprime: 3 × 107, the product of two primes.
- 2
321 is composite. Its prime factorisation is
- 3
The divisors add up to 432; without 321 itself that is 111, so 321 is deficient (111 is less than 321). Euler's totient φ(321) = 212 numbers up to 321 share no factor with it.
- 4
The digits of 321 add up to 6, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 24 steps to reach 1.
LaTeX source of the formulas on this page
\[ 321 = 3 \times 107 \]
321 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 432 |
| Euler totient φ(n) | 212 |
| Square | 103041 |
| Cube | 33076161 |
| Square root | 17.916473 |
| Digit sum / digital root | 6 / 6 |
| Collatz steps to 1 | 24 |
| Scientific notation | 3.21 × |
321 in other forms
| Form | Value |
|---|---|
| In words | three hundred and twenty-one |
| Roman numerals | CCCXXI |
| Binary (base 2) | 101000001 |
| Octal (base 8) | 501 |
| Hexadecimal (base 16) | 141 |
| Base 3 | 102220 |
| As time | 321 seconds = 5 min 21 s |
Is 321 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 (321 ÷ 3 = 107) | 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 3) | 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 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 1) | 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 321 a prime number?
No. 321 = 3 × 107, so it is divisible by 3.
What are the factors of 321?
1, 3, 107, 321.
What is 321 in binary?
101000001 (hexadecimal 141, octal 501).
What is the square root of 321?
About 17.9165.
What is 321 in Roman numerals?
CCCXXI.
Is 321 divisible by 3?
Yes. Its digits add up to 6, a multiple of 3.
What is special about the number 321?
321 is a semiprime: 3 × 107, the product of two primes.