42809391 has 10 divisors (see below), whose sum is σ = 63949952. Its totient is φ = 28539540.

The previous prime is 42809363. The next prime is 42809471. The reversal of 42809391 is 19390824.

42809391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 42809391 - 2¹⁴ = 42793007 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42809341) 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 9 ways as a sum of consecutive naturals, for example, 264175 + ... + 264336.

Almost surely, 2^42809391 is an apocalyptic number.

42809391 is a deficient number, since it is larger than the sum of its proper divisors (21140561).

42809391 is an equidigital number, since it uses as much as digits as its factorization.

42809391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528523 (or 528514 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 42809391 is about 6542.8885822701. Note that the first 3 decimals coincide. The cubic root of 42809391 is about 349.8213809679.

The spelling of 42809391 in words is "forty-two million, eight hundred nine thousand, three hundred ninety-one".