Number reference
243 explained.
243: two hundred forty-three, composite; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- two hundred forty-three
- Classification
- composite
- Factors
- 1, 3, 9, 27, 81, 243
- Prime factorization
- 3 × 3 × 3 × 3 × 3
- Square root
- 15.588457
- Cube root
- 6.240251
- Binary
- 11110011
- Octal
- 363
- Hexadecimal
- F3
- Roman numeral
- CCXLIII
- Digit sum
- 9
- Digital root
- 9
What makes 243 notable
- Factor structure. 243 breaks down into 1 distinct prime (3) and has 6 divisors in total, so it can be split into equal whole-number groups 4 ways beyond 1 and itself.
243 in everyday use
Two hundred forty-three is three to the fifth power, and it is very nearly the length of a day on Venus. The planet turns once on its axis every 243 Earth days, so slowly that its day is longer than its year of about 225 days, and it spins backwards relative to most planets. In computing, 243 is the number of five-digit strings you can write with three symbols, which is why a five-cell ternary display has 243 states. In Roman numerals it is CCXLIII.
As a power of three, 243 has exactly six divisors — 1, 3, 9, 27, 81, and 243 — and it is written 100000 in base three, 11110011 in binary, and F3 in hexadecimal. It is the last odd number below 245, and it sits between 242, which is 2 × 11², and 244, which is 4 × 61. Its digit sum is 9, a divisor of the number itself, so 243 is a Harshad number.
Nearby numbers
How to read this page
The factor list shows every way 243 splits into equal whole-number groups — 6 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 243 for contexts that do not use decimal.
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