The number 21103
21103 is a composite number with 4 divisors. Its prime factorisation is 47 × 449. Divisors (4): 1, 47, 449, 21103.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21103: a semiprime: 47 × 449, the product of two primes.
- 2
21103 is composite. Its prime factorisation is
- 3
The divisors add up to 21600; without 21103 itself that is 497, so 21103 is deficient (497 is less than 21103). Euler's totient φ(21103) = 20608 numbers up to 21103 share no factor with it.
- 4
The digits of 21103 add up to 7, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 79 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21103 = 47 \times 449 \]
21103 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 21600 |
| Euler totient φ(n) | 20608 |
| Square | 445336609 |
| Cube | 9397938459727 |
| Square root | 145.268717 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 79 |
| Scientific notation | 2.1103 × |
21103 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and three |
| Binary (base 2) | 101001001101111 |
| Octal (base 8) | 51157 |
| Hexadecimal (base 16) | 526F |
| Base 3 | 1001221121 |
| As time | 21103 seconds = 5 h 51 min 43 s |
Is 21103 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 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 1) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21103 a prime number?
No. 21103 = 47 × 449, so it is divisible by 47.
What are the factors of 21103?
1, 47, 449, 21103.
What is 21103 in binary?
101001001101111 (hexadecimal 526F, octal 51157).
What is the square root of 21103?
About 145.2687.
Is 21103 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 21103?
21103 is a semiprime: 47 × 449, the product of two primes.