42543661 has 4 divisors (see below), whose sum is σ = 43264800. Its totient is φ = 41822524.

The previous prime is 42543653. The next prime is 42543671. The reversal of 42543661 is 16634524.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 42543661 - 2³ = 42543653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42543671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 360481 + ... + 360598.

It is an arithmetic number, because the mean of its divisors is an integer number (10816200).

Almost surely, 2^42543661 is an apocalyptic number.

It is an amenable number.

42543661 is a deficient number, since it is larger than the sum of its proper divisors (721139).

42543661 is an equidigital number, since it uses as much as digits as its factorization.

42543661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721138.

The product of its digits is 17280, while the sum is 31.

The square root of 42543661 is about 6522.5501914512. The cubic root of 42543661 is about 349.0960647202.

The spelling of 42543661 in words is "forty-two million, five hundred forty-three thousand, six hundred sixty-one".