The number 15787
15787 is the 1841st prime number. Its only divisors are 1 and 15787.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15787: the 1841st prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
15787 is prime, so its only factors are 1 and 15787. It is the 1841st prime; the next prime is 15791 and the one before is 15773.
- 3
The divisors add up to 15788; without 15787 itself that is 1, so 15787 is deficient (1 is less than 15787). Euler's totient φ(15787) = 15786 numbers up to 15787 share no factor with it.
- 4
The digits of 15787 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 177 steps to reach 1.
15787 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 15788 |
| Euler totient φ(n) | 15786 |
| Square | 249229369 |
| Cube | 3934584048403 |
| Square root | 125.646329 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 177 |
| Scientific notation | 1.5787 × |
15787 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand seven hundred and eighty-seven |
| Binary (base 2) | 11110110101011 |
| Octal (base 8) | 36653 |
| Hexadecimal (base 16) | 3DAB |
| Base 3 | 210122201 |
| As time | 15787 seconds = 4 h 23 min 7 s |
Is 15787 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 | No (remainder 1) | 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 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | 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 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 15787 a prime number?
Yes. 15787 is divisible only by 1 and itself.
What are the factors of 15787?
1, 15787.
What is 15787 in binary?
11110110101011 (hexadecimal 3DAB, octal 36653).
What is the square root of 15787?
About 125.6463.
Is 15787 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 15787?
15787 is the 1841st prime number; a happy number: repeatedly adding the squares of its digits reaches 1.