The number 87990
87990 is a triangular number: 1 + 2 + … + 419 = 87990. Its prime factorisation is 2 × 3 × 5 × 7 × 419. Divisors (32): 1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70, 105, 210 … 87990.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 87990: a triangular number: 1 + 2 + … + 419 = 87990.
- 2
87990 is composite. Its prime factorisation is
- 3
The divisors add up to 241920; without 87990 itself that is 153930, so 87990 is abundant (153930 is more than 87990). Euler's totient φ(87990) = 20064 numbers up to 87990 share no factor with it.
- 4
The digits of 87990 add up to 33, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 120 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87990 = 2 \times 3 \times 5 \times 7 \times 419 \]
87990 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 241920 |
| Euler totient φ(n) | 20064 |
| Square | 7742240100 |
| Cube | 681239706399000 |
| Square root | 296.631084 |
| Digit sum / digital root | 33 / 6 |
| Collatz steps to 1 | 120 |
| Scientific notation | 8.799 × |
87990 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand nine hundred and ninety |
| Binary (base 2) | 10101011110110110 |
| Octal (base 8) | 253666 |
| Hexadecimal (base 16) | 157B6 |
| Base 3 | 11110200220 |
| As time | 87990 seconds = 24 h 26 min 30 s |
Is 87990 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (87990 ÷ 2 = 43995) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (87990 ÷ 3 = 29330) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (87990 ÷ 5 = 17598) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (87990 ÷ 6 = 14665) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (87990 ÷ 7 = 12570) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (87990 ÷ 10 = 8799) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87990 a prime number?
No. 87990 = 2 × 3 × 5 × 7 × 419, so it is divisible by 2.
What are the factors of 87990?
1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70, 105, 210, 419, 838, 1257, 2095, 2514, 2933, 4190, 5866, 6285, 8799, 12570, 14665, 17598, 29330, 43995, 87990.
What is 87990 in binary?
10101011110110110 (hexadecimal 157B6, octal 253666).
What is the square root of 87990?
About 296.6311.
Is 87990 divisible by 3?
Yes. Its digits add up to 33, a multiple of 3.
What is special about the number 87990?
87990 is a triangular number: 1 + 2 + … + 419 = 87990.