The number 7521
7521 is a composite number with 8 divisors. Its prime factorisation is 3 × 23 × 109. Divisors (8): 1, 3, 23, 69, 109, 327, 2507, 7521.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7521: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
7521 is composite. Its prime factorisation is
- 3
The divisors add up to 10560; without 7521 itself that is 3039, so 7521 is deficient (3039 is less than 7521). Euler's totient φ(7521) = 4752 numbers up to 7521 share no factor with it.
- 4
The digits of 7521 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 44 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7521 = 3 \times 23 \times 109 \]
7521 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 10560 |
| Euler totient φ(n) | 4752 |
| Square | 56565441 |
| Cube | 425428681761 |
| Square root | 86.723699 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 44 |
| Scientific notation | 7.521 × |
7521 in other forms
| Form | Value |
|---|---|
| In words | seven thousand five hundred and twenty-one |
| Binary (base 2) | 1110101100001 |
| Octal (base 8) | 16541 |
| Hexadecimal (base 16) | 1D61 |
| Base 3 | 101022120 |
| As time | 7521 seconds = 2 h 5 min 21 s |
Is 7521 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 (7521 ÷ 3 = 2507) | 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 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 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 8) | 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 7521 a prime number?
No. 7521 = 3 × 23 × 109, so it is divisible by 3.
What are the factors of 7521?
1, 3, 23, 69, 109, 327, 2507, 7521.
What is 7521 in binary?
1110101100001 (hexadecimal 1D61, octal 16541).
What is the square root of 7521?
About 86.7237.
Is 7521 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 7521?
7521 is a happy number: repeatedly adding the squares of its digits reaches 1.