The number 15771
15771 is a composite number with 8 divisors. Its prime factorisation is 3 × 7 × 751. Divisors (8): 1, 3, 7, 21, 751, 2253, 5257, 15771.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15771: a Harshad number: divisible by its digit sum 21.
- 2
15771 is composite. Its prime factorisation is
- 3
The divisors add up to 24064; without 15771 itself that is 8293, so 15771 is deficient (8293 is less than 15771). Euler's totient φ(15771) = 9000 numbers up to 15771 share no factor with it.
- 4
The digits of 15771 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 84 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15771 = 3 \times 7 \times 751 \]
15771 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 24064 |
| Euler totient φ(n) | 9000 |
| Square | 248724441 |
| Cube | 3922633159011 |
| Square root | 125.582642 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 84 |
| Scientific notation | 1.5771 × |
15771 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand seven hundred and seventy-one |
| Binary (base 2) | 11110110011011 |
| Octal (base 8) | 36633 |
| Hexadecimal (base 16) | 3D9B |
| Base 3 | 210122010 |
| As time | 15771 seconds = 4 h 22 min 51 s |
Is 15771 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 (15771 ÷ 3 = 5257) | 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 | Yes (15771 ÷ 7 = 2253) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 8) | 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 15771 a prime number?
No. 15771 = 3 × 7 × 751, so it is divisible by 3.
What are the factors of 15771?
1, 3, 7, 21, 751, 2253, 5257, 15771.
What is 15771 in binary?
11110110011011 (hexadecimal 3D9B, octal 36633).
What is the square root of 15771?
About 125.5826.
Is 15771 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 15771?
15771 is a Harshad number: divisible by its digit sum 21.