42805021 has 4 divisors (see below), whose sum is σ = 48920032. Its totient is φ = 36690012.

The previous prime is 42805019. The next prime is 42805051. The reversal of 42805021 is 12050824.

42805021 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 42805021 - 2¹ = 42805019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 42804983 and 42805001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42805051) 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, 3057495 + ... + 3057508.

It is an arithmetic number, because the mean of its divisors is an integer number (12230008).

Almost surely, 2^42805021 is an apocalyptic number.

It is an amenable number.

42805021 is a deficient number, since it is larger than the sum of its proper divisors (6115011).

42805021 is an equidigital number, since it uses as much as digits as its factorization.

42805021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6115010.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 42805021 is about 6542.5546233868. The cubic root of 42805021 is about 349.8094772600.

Adding to 42805021 its reverse (12050824), we get a palindrome (54855845).

The spelling of 42805021 in words is "forty-two million, eight hundred five thousand, twenty-one".