The number 403
403 is a binary palindrome (110010011). Its prime factorisation is 13 × 31. Divisors (4): 1, 13, 31, 403.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 403: a binary palindrome (110010011); a semiprime: 13 × 31, the product of two primes.
- 2
403 is composite. Its prime factorisation is
- 3
The divisors add up to 448; without 403 itself that is 45, so 403 is deficient (45 is less than 403). Euler's totient φ(403) = 360 numbers up to 403 share no factor with it.
- 4
The digits of 403 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 19 steps to reach 1.
LaTeX source of the formulas on this page
\[ 403 = 13 \times 31 \]
403 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 448 |
| Euler totient φ(n) | 360 |
| Square | 162409 |
| Cube | 65450827 |
| Square root | 20.074860 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 19 |
| Scientific notation | 4.03 × |
403 in other forms
| Form | Value |
|---|---|
| In words | four hundred and three |
| Roman numerals | CDIII |
| Binary (base 2) | 110010011 |
| Octal (base 8) | 623 |
| Hexadecimal (base 16) | 193 |
| Base 3 | 112221 |
| As time | 403 seconds = 6 min 43 s |
Is 403 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 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 3) | 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 7) | 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 403 a prime number?
No. 403 = 13 × 31, so it is divisible by 13.
What are the factors of 403?
1, 13, 31, 403.
What is 403 in binary?
110010011 (hexadecimal 193, octal 623).
What is the square root of 403?
About 20.0749.
What is 403 in Roman numerals?
CDIII.
Is 403 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 403?
403 is a binary palindrome (110010011); a semiprime: 13 × 31, the product of two primes.