The number 253
253 is a triangular number: 1 + 2 + … + 22 = 253. Its prime factorisation is 11 × 23. Divisors (4): 1, 11, 23, 253.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 253: a triangular number: 1 + 2 + … + 22 = 253; a semiprime: 11 × 23, the product of two primes.
- 2
253 is composite. Its prime factorisation is
- 3
The divisors add up to 288; without 253 itself that is 35, so 253 is deficient (35 is less than 253). Euler's totient φ(253) = 220 numbers up to 253 share no factor with it.
- 4
The digits of 253 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 109 steps to reach 1.
LaTeX source of the formulas on this page
\[ 253 = 11 \times 23 \]
253 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 288 |
| Euler totient φ(n) | 220 |
| Square | 64009 |
| Cube | 16194277 |
| Square root | 15.905974 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 109 |
| Scientific notation | 2.53 × |
253 in other forms
| Form | Value |
|---|---|
| In words | two hundred and fifty-three |
| Roman numerals | CCLIII |
| Binary (base 2) | 11111101 |
| Octal (base 8) | 375 |
| Hexadecimal (base 16) | FD |
| Base 3 | 100101 |
| As time | 253 seconds = 4 min 13 s |
Is 253 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 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 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 1) | 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 | Yes (253 ÷ 11 = 23) | 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 253 a prime number?
No. 253 = 11 × 23, so it is divisible by 11.
What are the factors of 253?
1, 11, 23, 253.
What is 253 in binary?
11111101 (hexadecimal FD, octal 375).
What is the square root of 253?
About 15.9060.
What is 253 in Roman numerals?
CCLIII.
Is 253 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 253?
253 is a triangular number: 1 + 2 + … + 22 = 253; a semiprime: 11 × 23, the product of two primes.