The number 21418
21418 is a composite number with 4 divisors. Its prime factorisation is 2 × 10709. Divisors (4): 1, 2, 10709, 21418.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21418: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10709, the product of two primes.
- 2
21418 is composite. Its prime factorisation is
- 3
The divisors add up to 32130; without 21418 itself that is 10712, so 21418 is deficient (10712 is less than 21418). Euler's totient φ(21418) = 10708 numbers up to 21418 share no factor with it.
- 4
The digits of 21418 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 74 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21418 = 2 \times 10709 \]
21418 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 32130 |
| Euler totient φ(n) | 10708 |
| Square | 458730724 |
| Cube | 9825094646632 |
| Square root | 146.348898 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 74 |
| Scientific notation | 2.1418 × |
21418 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and eighteen |
| Binary (base 2) | 101001110101010 |
| Octal (base 8) | 51652 |
| Hexadecimal (base 16) | 53AA |
| Base 3 | 1002101021 |
| As time | 21418 seconds = 5 h 56 min 58 s |
Is 21418 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21418 ÷ 2 = 10709) | 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 2) | 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 4) | 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 2) | 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 8) | 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 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21418 a prime number?
No. 21418 = 2 × 10709, so it is divisible by 2.
What are the factors of 21418?
1, 2, 10709, 21418.
What is 21418 in binary?
101001110101010 (hexadecimal 53AA, octal 51652).
What is the square root of 21418?
About 146.3489.
Is 21418 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 21418?
21418 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10709, the product of two primes.