42185809 has 4 divisors (see below), whose sum is σ = 43326004. Its totient is φ = 41045616.

The previous prime is 42185797. The next prime is 42185839. The reversal of 42185809 is 90858124.

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 37859409 + 4326400 = 6153^2 + 2080^2 .

It is a cyclic number.

It is not a de Polignac number, because 42185809 - 2¹⁷ = 42054737 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 1140157 = 42185809 / (4 + 2 + 1 + 8 + 5 + 8 + 0 + 9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42185839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 570042 + ... + 570115.

It is an arithmetic number, because the mean of its divisors is an integer number (10831501).

Almost surely, 2^42185809 is an apocalyptic number.

It is an amenable number.

42185809 is a deficient number, since it is larger than the sum of its proper divisors (1140195).

42185809 is a wasteful number, since it uses less digits than its factorization.

42185809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1140194.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 42185809 is about 6495.0603538381. The cubic root of 42185809 is about 348.1145112430.

The spelling of 42185809 in words is "forty-two million, one hundred eighty-five thousand, eight hundred nine".