The number 61521
61521 is a composite number with 4 divisors. Its prime factorisation is 3 × 20507. Divisors (4): 1, 3, 20507, 61521.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 61521: a semiprime: 3 × 20507, the product of two primes.
- 2
61521 is composite. Its prime factorisation is
- 3
The divisors add up to 82032; without 61521 itself that is 20511, so 61521 is deficient (20511 is less than 61521). Euler's totient φ(61521) = 41012 numbers up to 61521 share no factor with it.
- 4
The digits of 61521 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 60 steps to reach 1.
LaTeX source of the formulas on this page
\[ 61521 = 3 \times 20507 \]
61521 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 82032 |
| Euler totient φ(n) | 41012 |
| Square | 3784833441 |
| Cube | 232846738123761 |
| Square root | 248.034272 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 60 |
| Scientific notation | 6.1521 × |
61521 in other forms
| Form | Value |
|---|---|
| In words | sixty-one thousand five hundred and twenty-one |
| Binary (base 2) | 1111000001010001 |
| Octal (base 8) | 170121 |
| Hexadecimal (base 16) | F051 |
| Base 3 | 10010101120 |
| As time | 61521 seconds = 17 h 5 min 21 s |
Is 61521 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 | Yes (61521 ÷ 3 = 20507) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 1) | 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 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 61521 a prime number?
No. 61521 = 3 × 20507, so it is divisible by 3.
What are the factors of 61521?
1, 3, 20507, 61521.
What is 61521 in binary?
1111000001010001 (hexadecimal F051, octal 170121).
What is the square root of 61521?
About 248.0343.
Is 61521 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 61521?
61521 is a semiprime: 3 × 20507, the product of two primes.