Number
43
- Positive
- Odd
- Prime
- 2 digits
43 is an odd 2-digit integer and a prime number. It has 2 divisors and a digital root of 7.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityPrime
Absolute value43
Digit count2
Digit sum7
Digital root7repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation43
Distinct prime factors143
Number of divisors2
Sum of divisors σ(n)44
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)42integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 432 in total
Arithmetic
Representations
Decimal43
Binary1010116 bits
Octal53
Hexadecimal2B
Base 3617
Roman numeralXLIII
In wordsforty-three
Ordinalforty-third
Scientific notation4.3 × 10^1
Engineering notation43
Nearest landmarks
Powers & multiples
43 to the power 21,849
43 to the power 379,507
43 to the power 43,418,801
43 to the power 5147,008,443
First ten multiples43, 86, 129, 172, 215, 258, 301, 344, 387, 430
Powers of twoBetween 2^5 (32) and 2^6 (64)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3No, remainder 1
Divisible by 4No, remainder 3
Divisible by 5No, remainder 3
Divisible by 6No, remainder 1
Divisible by 7No, remainder 1
Divisible by 8No, remainder 3
Divisible by 9No, remainder 7
Divisible by 10No, remainder 3
Divisible by 11No, remainder 10
Divisible by 12No, remainder 7
Divisible by 100No, remainder 43
Collatz (3n + 1) trajectory
Steps to reach 129the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps43 → 130 → 65 → 196 → 98 → 49 → 148 → 74 → 37 → 112 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage4,300%
43% as a decimal0.43
43% of 10043
43% of 1,000430
As a fraction of 10043/100
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