Number reference
43 explained.
43: forty-three, prime; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- forty-three
- Classification
- prime
- Factors
- 1, 43
- Prime factorization
- 43
- Square root
- 6.557439
- Cube root
- 3.503398
- Binary
- 101011
- Octal
- 53
- Hexadecimal
- 2B
- Roman numeral
- XLIII
- Digit sum
- 7
- Digital root
- 7
What makes 43 notable
- Prime. 43 is prime: it has exactly two divisors, 1 and itself, so it cannot be split into equal whole-number groups any other way.
43 in everyday use
Forty-three is the atomic number of technetium, the first element to be made artificially, in 1937, and the lightest element with no stable isotope. George W. Bush was the 43rd President of the United States. Forty-three is the number of Chicken McNuggets in the classic puzzle: with boxes of 6, 9, and 20, 43 is the largest order that cannot be filled exactly.
Forty-three is the fourteenth prime and the larger half of the twin pair 41 and 43. It is the sum of a cube and a square, 27 + 16, and it is written 111 in base 6, since 36 + 6 + 1 = 43. In binary it is 101011. It leaves a remainder of 3 when divided by 4, so unlike its twin 41 it cannot be written as the sum of two squares.
Nearby numbers
How to read this page
Because 43 is prime, the factor list stops at 1 and 43 itself, so it cannot be shared into equal whole-number groups. That is also what makes it useful as a building block: every larger number with 43 in its prime factorisation inherits it from here.
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