The number 25987
25987 is a composite number with 4 divisors. Its prime factorisation is 13 × 1999. Divisors (4): 1, 13, 1999, 25987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 25987: a semiprime: 13 × 1999, the product of two primes.
- 2
25987 is composite. Its prime factorisation is
- 3
The divisors add up to 28000; without 25987 itself that is 2013, so 25987 is deficient (2013 is less than 25987). Euler's totient φ(25987) = 23976 numbers up to 25987 share no factor with it.
- 4
The digits of 25987 add up to 31, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 139 steps to reach 1.
LaTeX source of the formulas on this page
\[ 25987 = 13 \times 1999 \]
25987 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 28000 |
| Euler totient φ(n) | 23976 |
| Square | 675324169 |
| Cube | 17549649179803 |
| Square root | 161.204839 |
| Digit sum / digital root | 31 / 4 |
| Collatz steps to 1 | 139 |
| Scientific notation | 2.5987 × |
25987 in other forms
| Form | Value |
|---|---|
| In words | twenty-five thousand nine hundred and eighty-seven |
| Binary (base 2) | 110010110000011 |
| Octal (base 8) | 62603 |
| Hexadecimal (base 16) | 6583 |
| Base 3 | 1022122111 |
| As time | 25987 seconds = 7 h 13 min 7 s |
Is 25987 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 3) | 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 4) | 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 5) | 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 25987 a prime number?
No. 25987 = 13 × 1999, so it is divisible by 13.
What are the factors of 25987?
1, 13, 1999, 25987.
What is 25987 in binary?
110010110000011 (hexadecimal 6583, octal 62603).
What is the square root of 25987?
About 161.2048.
Is 25987 divisible by 3?
No. Its digits add up to 31, which is not a multiple of 3.
What is special about the number 25987?
25987 is a semiprime: 13 × 1999, the product of two primes.