42543581 has 2 divisors, whose sum is σ = 42543582. Its totient is φ = 42543580.

The previous prime is 42543547. The next prime is 42543617. The reversal of 42543581 is 18534524.

42543581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31922500 + 10621081 = 5650^2 + 3259^2 .

It is a cyclic number.

It is not a de Polignac number, because 42543581 - 2⁶ = 42543517 is a prime.

It is a super-2 number, since 2×42543581² = 3619912568607122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42543511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21271790 + 21271791.

It is an arithmetic number, because the mean of its divisors is an integer number (21271791).

Almost surely, 2^42543581 is an apocalyptic number.

It is an amenable number.

42543581 is a deficient number, since it is larger than the sum of its proper divisors (1).

42543581 is an equidigital number, since it uses as much as digits as its factorization.

42543581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19200, while the sum is 32.

The square root of 42543581 is about 6522.5440588776. The cubic root of 42543581 is about 349.0958459042.

The spelling of 42543581 in words is "forty-two million, five hundred forty-three thousand, five hundred eighty-one".