The number 79987
79987 is the 7835th prime number. Its only divisors are 1 and 79987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 79987: the 7835th prime number.
- 2
79987 is prime, so its only factors are 1 and 79987. It is the 7835th prime; the next prime is 79997 and the one before is 79979.
- 3
The divisors add up to 79988; without 79987 itself that is 1, so 79987 is deficient (1 is less than 79987). Euler's totient φ(79987) = 79986 numbers up to 79987 share no factor with it.
- 4
The digits of 79987 add up to 40, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 68 steps to reach 1.
79987 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 79988 |
| Euler totient φ(n) | 79986 |
| Square | 6397920169 |
| Cube | 511750440557803 |
| Square root | 282.819731 |
| Digit sum / digital root | 40 / 4 |
| Collatz steps to 1 | 68 |
| Scientific notation | 7.9987 × |
79987 in other forms
| Form | Value |
|---|---|
| In words | seventy-nine thousand nine hundred and eighty-seven |
| Binary (base 2) | 10011100001110011 |
| Octal (base 8) | 234163 |
| Hexadecimal (base 16) | 13873 |
| Base 3 | 11001201111 |
| As time | 79987 seconds = 22 h 13 min 7 s |
Is 79987 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 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 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 6) | 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 79987 a prime number?
Yes. 79987 is divisible only by 1 and itself.
What are the factors of 79987?
1, 79987.
What is 79987 in binary?
10011100001110011 (hexadecimal 13873, octal 234163).
What is the square root of 79987?
About 282.8197.
Is 79987 divisible by 3?
No. Its digits add up to 40, which is not a multiple of 3.
What is special about the number 79987?
79987 is the 7835th prime number.