43
43 is a prime number, the atomic number of technetium — the first element ever produced artificially — and forms a twin-prime pair with 41.
- Odd
- Prime
Where 43 fits
Why 43 is special
43's element, technetium, is scientifically notable in its own right: every atom of it in a lab was made by humans, none found naturally on Earth in any practical quantity.
43 is part of
Factors & digit properties
- Divisors (2)
- 1, 43
- Prime factorisation
- 43
- Digit sum
- 7
- Digital root
- 7
Representations
- Decimal
- 43
- Binary
- 101011
- Octal
- 53
- Hexadecimal
- 2b
- Roman numeral
- XLIII
- Scientific notation
- 4.300 × 10^1
Other mathematical patterns
- Deficient number
- Lucky number (mathematical sieve)
- Twin prime
Related numbers & connections
43 is a factor of 86 (43 × 2 = 86).
View 86 →41 and 43 are twin primes — two primes exactly two apart.
View 41 →Science
43 is the atomic number of technetium, the first chemical element to be produced artificially rather than found in nature.
DocumentedScience
Mathematics
43 is prime, and forms a twin-prime pair with 41.
DocumentedMathematics
Common questions
Is 43 a prime number?
Yes, 43 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 43?
The factors of 43 are 1, 43.
What is 43 in Roman numerals?
43 in Roman numerals is XLIII.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026