42531721 has 4 divisors (see below), whose sum is σ = 43903744. Its totient is φ = 41159700.

The previous prime is 42531707. The next prime is 42531737. The reversal of 42531721 is 12713524.

It is a happy number.

42531721 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 42531721 - 2²³ = 34143113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42531781) 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, 685965 + ... + 686026.

It is an arithmetic number, because the mean of its divisors is an integer number (10975936).

Almost surely, 2^42531721 is an apocalyptic number.

It is an amenable number.

42531721 is a deficient number, since it is larger than the sum of its proper divisors (1372023).

42531721 is a wasteful number, since it uses less digits than its factorization.

42531721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1372022.

The product of its digits is 1680, while the sum is 25.

The square root of 42531721 is about 6521.6348410502. The cubic root of 42531721 is about 349.0634033952.

The spelling of 42531721 in words is "forty-two million, five hundred thirty-one thousand, seven hundred twenty-one".