20904185 has 4 divisors (see below), whose sum is σ = 25085028. Its totient is φ = 16723344.

The previous prime is 20904181. The next prime is 20904193. The reversal of 20904185 is 58140902.

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 14891881 + 6012304 = 3859^2 + 2452^2 .

It is a cyclic number.

It is not a de Polignac number, because 20904185 - 2² = 20904181 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20904181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2090414 + ... + 2090423.

It is an arithmetic number, because the mean of its divisors is an integer number (6271257).

Almost surely, 2^20904185 is an apocalyptic number.

It is an amenable number.

20904185 is a deficient number, since it is larger than the sum of its proper divisors (4180843).

20904185 is an equidigital number, since it uses as much as digits as its factorization.

20904185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4180842.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 20904185 is about 4572.1094693806. The cubic root of 20904185 is about 275.4721805281.

The spelling of 20904185 in words is "twenty million, nine hundred four thousand, one hundred eighty-five".