42731809 has 4 divisors (see below), whose sum is σ = 43725616. Its totient is φ = 41738004.

The previous prime is 42731783. The next prime is 42731813. The reversal of 42731809 is 90813724.

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 42731809 - 2⁷ = 42731681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42731849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 496839 + ... + 496924.

It is an arithmetic number, because the mean of its divisors is an integer number (10931404).

Almost surely, 2^42731809 is an apocalyptic number.

It is an amenable number.

42731809 is a deficient number, since it is larger than the sum of its proper divisors (993807).

42731809 is an equidigital number, since it uses as much as digits as its factorization.

42731809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 993806.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 42731809 is about 6536.9571667558. The cubic root of 42731809 is about 349.6099300600.

The spelling of 42731809 in words is "forty-two million, seven hundred thirty-one thousand, eight hundred nine".