42638681 has 4 divisors (see below), whose sum is σ = 42900432. Its totient is φ = 42376932.

The previous prime is 42638663. The next prime is 42638693. The reversal of 42638681 is 18683624.

It is a happy number.

42638681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 42638681 - 2¹⁴ = 42622297 is a prime.

It is a super-2 number, since 2×42638681² = 3636114234839522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (42638611) 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 in 3 ways as a sum of consecutive naturals, for example, 130631 + ... + 130956.

It is an arithmetic number, because the mean of its divisors is an integer number (10725108).

Almost surely, 2^42638681 is an apocalyptic number.

It is an amenable number.

42638681 is a deficient number, since it is larger than the sum of its proper divisors (261751).

42638681 is a wasteful number, since it uses less digits than its factorization.

42638681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261750.

The product of its digits is 55296, while the sum is 38.

The square root of 42638681 is about 6529.8300896731. The cubic root of 42638681 is about 349.3557700231.

The spelling of 42638681 in words is "forty-two million, six hundred thirty-eight thousand, six hundred eighty-one".