The number 351
351 is a triangular number: 1 + 2 + … + 26 = 351. Its prime factorisation is × 13. Divisors (8): 1, 3, 9, 13, 27, 39, 117, 351.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 351: a triangular number: 1 + 2 + … + 26 = 351; a Harshad number: divisible by its digit sum 9.
- 2
351 is composite. Its prime factorisation is
- 3
The divisors add up to 560; without 351 itself that is 209, so 351 is deficient (209 is less than 351). Euler's totient φ(351) = 216 numbers up to 351 share no factor with it.
- 4
The digits of 351 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 81 steps to reach 1.
LaTeX source of the formulas on this page
\[ 351 = 3^{3} \times 13 \]351 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 560 |
| Euler totient φ(n) | 216 |
| Square | 123201 |
| Cube | 43243551 |
| Square root | 18.734994 (= 3√39) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 81 |
| Scientific notation | 3.51 × |
351 in other forms
| Form | Value |
|---|---|
| In words | three hundred and fifty-one |
| Roman numerals | CCCLI |
| Binary (base 2) | 101011111 |
| Octal (base 8) | 537 |
| Hexadecimal (base 16) | 15F |
| Base 3 | 111000 |
| As time | 351 seconds = 5 min 51 s |
Is 351 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 (351 ÷ 3 = 117) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 1) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (351 ÷ 9 = 39) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 351 a prime number?
No. 351 = × 13, so it is divisible by 3.
What are the factors of 351?
1, 3, 9, 13, 27, 39, 117, 351.
What is 351 in binary?
101011111 (hexadecimal 15F, octal 537).
What is the square root of 351?
About 18.7350, exactly 3√39.
What is 351 in Roman numerals?
CCCLI.
Is 351 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 351?
351 is a triangular number: 1 + 2 + … + 26 = 351; a Harshad number: divisible by its digit sum 9.