20928609 has 12 divisors (see below), whose sum is σ = 32555796. Its totient is φ = 12879072.

The previous prime is 20928541. The next prime is 20928629. The reversal of 20928609 is 90682902.

20928609 is a `hidden beast` number, since 20 + 9 + 28 + 609 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6275025 + 14653584 = 2505^2 + 3828^2 .

It is not a de Polignac number, because 20928609 - 2⁸ = 20928353 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20928629) 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 11 ways as a sum of consecutive naturals, for example, 89322 + ... + 89555.

It is an arithmetic number, because the mean of its divisors is an integer number (2712983).

Almost surely, 2^20928609 is an apocalyptic number.

It is an amenable number.

20928609 is a deficient number, since it is larger than the sum of its proper divisors (11627187).

20928609 is a wasteful number, since it uses less digits than its factorization.

20928609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178896 (or 178893 counting only the distinct ones).

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

The square root of 20928609 is about 4574.7796668255. The cubic root of 20928609 is about 275.5794240282.

It can be divided in two parts, 2092 and 8609, that added together give a palindrome (10701).

The spelling of 20928609 in words is "twenty million, nine hundred twenty-eight thousand, six hundred nine".