The number 15990
15990 is a composite number with 32 divisors. Its prime factorisation is 2 × 3 × 5 × 13 × 41. Divisors (32): 1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 41, 65, 78, 82, 123 … 15990.
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How to work it out
- 1
What is special about 15990: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
15990 is composite. Its prime factorisation is
- 3
The divisors add up to 42336; without 15990 itself that is 26346, so 15990 is abundant (26346 is more than 15990). Euler's totient φ(15990) = 3840 numbers up to 15990 share no factor with it.
- 4
The digits of 15990 add up to 24, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 53 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15990 = 2 \times 3 \times 5 \times 13 \times 41 \]
15990 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 42336 |
| Euler totient φ(n) | 3840 |
| Square | 255680100 |
| Cube | 4088324799000 |
| Square root | 126.451572 |
| Digit sum / digital root | 24 / 6 |
| Collatz steps to 1 | 53 |
| Scientific notation | 1.599 × |
15990 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand nine hundred and ninety |
| Binary (base 2) | 11111001110110 |
| Octal (base 8) | 37166 |
| Hexadecimal (base 16) | 3E76 |
| Base 3 | 210221020 |
| As time | 15990 seconds = 4 h 26 min 30 s |
Is 15990 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (15990 ÷ 2 = 7995) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (15990 ÷ 3 = 5330) | 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 (15990 ÷ 5 = 3198) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (15990 ÷ 6 = 2665) | 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 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 (15990 ÷ 10 = 1599) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | 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 15990 a prime number?
No. 15990 = 2 × 3 × 5 × 13 × 41, so it is divisible by 2.
What are the factors of 15990?
1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 41, 65, 78, 82, 123, 130, 195, 205, 246, 390, 410, 533, 615, 1066, 1230, 1599, 2665, 3198, 5330, 7995, 15990.
What is 15990 in binary?
11111001110110 (hexadecimal 3E76, octal 37166).
What is the square root of 15990?
About 126.4516.
Is 15990 divisible by 3?
Yes. Its digits add up to 24, a multiple of 3.
What is special about the number 15990?
15990 is a happy number: repeatedly adding the squares of its digits reaches 1.