The number 621
621 is a composite number with 8 divisors. Its prime factorisation is × 23. Divisors (8): 1, 3, 9, 23, 27, 69, 207, 621.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 621: a Harshad number: divisible by its digit sum 9.
- 2
621 is composite. Its prime factorisation is
- 3
The divisors add up to 960; without 621 itself that is 339, so 621 is deficient (339 is less than 621). Euler's totient φ(621) = 396 numbers up to 621 share no factor with it.
- 4
The digits of 621 add up to 9, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 87 steps to reach 1.
LaTeX source of the formulas on this page
\[ 621 = 3^{3} \times 23 \]621 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 960 |
| Euler totient φ(n) | 396 |
| Square | 385641 |
| Cube | 239483061 |
| Square root | 24.919872 (= 3√69) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 87 |
| Scientific notation | 6.21 × |
621 in other forms
| Form | Value |
|---|---|
| In words | six hundred and twenty-one |
| Roman numerals | DCXXI |
| Binary (base 2) | 1001101101 |
| Octal (base 8) | 1155 |
| Hexadecimal (base 16) | 26D |
| Base 3 | 212000 |
| As time | 621 seconds = 10 min 21 s |
Is 621 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 (621 ÷ 3 = 207) | 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 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 | Yes (621 ÷ 9 = 69) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 621 a prime number?
No. 621 = × 23, so it is divisible by 3.
What are the factors of 621?
1, 3, 9, 23, 27, 69, 207, 621.
What is 621 in binary?
1001101101 (hexadecimal 26D, octal 1155).
What is the square root of 621?
About 24.9199, exactly 3√69.
What is 621 in Roman numerals?
DCXXI.
Is 621 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 621?
621 is a Harshad number: divisible by its digit sum 9.