The number 21473
21473 is a composite number with 4 divisors. Its prime factorisation is 109 × 197. Divisors (4): 1, 109, 197, 21473.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21473: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 109 × 197, the product of two primes.
- 2
21473 is composite. Its prime factorisation is
- 3
The divisors add up to 21780; without 21473 itself that is 307, so 21473 is deficient (307 is less than 21473). Euler's totient φ(21473) = 21168 numbers up to 21473 share no factor with it.
- 4
The digits of 21473 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 48 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21473 = 109 \times 197 \]
21473 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 21780 |
| Euler totient φ(n) | 21168 |
| Square | 461089729 |
| Cube | 9900979750817 |
| Square root | 146.536685 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.1473 × |
21473 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and seventy-three |
| Binary (base 2) | 101001111100001 |
| Octal (base 8) | 51741 |
| Hexadecimal (base 16) | 53E1 |
| Base 3 | 1002110022 |
| As time | 21473 seconds = 5 h 57 min 53 s |
Is 21473 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 | No (remainder 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 8) | 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 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21473 a prime number?
No. 21473 = 109 × 197, so it is divisible by 109.
What are the factors of 21473?
1, 109, 197, 21473.
What is 21473 in binary?
101001111100001 (hexadecimal 53E1, octal 51741).
What is the square root of 21473?
About 146.5367.
Is 21473 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 21473?
21473 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 109 × 197, the product of two primes.