42808921 has 4 divisors (see below), whose sum is σ = 42902244. Its totient is φ = 42715600.

The previous prime is 42808897. The next prime is 42808937. The reversal of 42808921 is 12980824.

42808921 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.

It can be written as a sum of positive squares in 2 ways, for example, as 6375625 + 36433296 = 2525^2 + 6036^2 .

It is a cyclic number.

It is not a de Polignac number, because 42808921 - 2¹¹ = 42806873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42808991) 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, 45970 + ... + 46891.

It is an arithmetic number, because the mean of its divisors is an integer number (10725561).

Almost surely, 2^42808921 is an apocalyptic number.

It is an amenable number.

42808921 is a deficient number, since it is larger than the sum of its proper divisors (93323).

42808921 is an equidigital number, since it uses as much as digits as its factorization.

42808921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93322.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 42808921 is about 6542.8526653135. The cubic root of 42808921 is about 349.8201007453.

The spelling of 42808921 in words is "forty-two million, eight hundred eight thousand, nine hundred twenty-one".