The number 21513
21513 is a composite number with 8 divisors. Its prime factorisation is 3 × 71 × 101. Divisors (8): 1, 3, 71, 101, 213, 303, 7171, 21513.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21513 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21513 is composite. Its prime factorisation is
- 3
The divisors add up to 29376; without 21513 itself that is 7863, so 21513 is deficient (7863 is less than 21513). Euler's totient φ(21513) = 14000 numbers up to 21513 share no factor with it.
- 4
The digits of 21513 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 74 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21513 = 3 \times 71 \times 101 \]
21513 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 29376 |
| Euler totient φ(n) | 14000 |
| Square | 462809169 |
| Cube | 9956413652697 |
| Square root | 146.673106 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 74 |
| Scientific notation | 2.1513 × |
21513 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and thirteen |
| Binary (base 2) | 101010000001001 |
| Octal (base 8) | 52011 |
| Hexadecimal (base 16) | 5409 |
| Base 3 | 1002111210 |
| As time | 21513 seconds = 5 h 58 min 33 s |
Is 21513 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 (21513 ÷ 3 = 7171) | 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 3) | 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 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | 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 21513 a prime number?
No. 21513 = 3 × 71 × 101, so it is divisible by 3.
What are the factors of 21513?
1, 3, 71, 101, 213, 303, 7171, 21513.
What is 21513 in binary?
101010000001001 (hexadecimal 5409, octal 52011).
What is the square root of 21513?
About 146.6731.
Is 21513 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 21513?
It is a composite number with 8 divisors.