The number 7421
7421 is a composite number with 4 divisors. Its prime factorisation is 41 × 181. Divisors (4): 1, 41, 181, 7421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7421: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 41 × 181, the product of two primes.
- 2
7421 is composite. Its prime factorisation is
- 3
The divisors add up to 7644; without 7421 itself that is 223, so 7421 is deficient (223 is less than 7421). Euler's totient φ(7421) = 7200 numbers up to 7421 share no factor with it.
- 4
The digits of 7421 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 119 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7421 = 41 \times 181 \]
7421 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 7644 |
| Euler totient φ(n) | 7200 |
| Square | 55071241 |
| Cube | 408683679461 |
| Square root | 86.145226 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 119 |
| Scientific notation | 7.421 × |
7421 in other forms
| Form | Value |
|---|---|
| In words | seven thousand four hundred and twenty-one |
| Binary (base 2) | 1110011111101 |
| Octal (base 8) | 16375 |
| Hexadecimal (base 16) | 1CFD |
| Base 3 | 101011212 |
| As time | 7421 seconds = 2 h 3 min 41 s |
Is 7421 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 1) | 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 1) | 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 5) | 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 7) | 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 7421 a prime number?
No. 7421 = 41 × 181, so it is divisible by 41.
What are the factors of 7421?
1, 41, 181, 7421.
What is 7421 in binary?
1110011111101 (hexadecimal 1CFD, octal 16375).
What is the square root of 7421?
About 86.1452.
Is 7421 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 7421?
7421 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 41 × 181, the product of two primes.