The number 15421
15421 is a composite number with 4 divisors. Its prime factorisation is 7 × 2203. Divisors (4): 1, 7, 2203, 15421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15421: a semiprime: 7 × 2203, the product of two primes.
- 2
15421 is composite. Its prime factorisation is
- 3
The divisors add up to 17632; without 15421 itself that is 2211, so 15421 is deficient (2211 is less than 15421). Euler's totient φ(15421) = 13212 numbers up to 15421 share no factor with it.
- 4
The digits of 15421 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 53 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15421 = 7 \times 2203 \]
15421 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 17632 |
| Euler totient φ(n) | 13212 |
| Square | 237807241 |
| Cube | 3667225463461 |
| Square root | 124.181319 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 53 |
| Scientific notation | 1.5421 × |
15421 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand four hundred and twenty-one |
| Binary (base 2) | 11110000111101 |
| Octal (base 8) | 36075 |
| Hexadecimal (base 16) | 3C3D |
| Base 3 | 210011011 |
| As time | 15421 seconds = 4 h 17 min 1 s |
Is 15421 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 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (15421 ÷ 7 = 2203) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 15421 a prime number?
No. 15421 = 7 × 2203, so it is divisible by 7.
What are the factors of 15421?
1, 7, 2203, 15421.
What is 15421 in binary?
11110000111101 (hexadecimal 3C3D, octal 36075).
What is the square root of 15421?
About 124.1813.
Is 15421 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 15421?
15421 is a semiprime: 7 × 2203, the product of two primes.