20664609 has 32 divisors (see below), whose sum is σ = 33684480. Its totient is φ = 11005632.

The previous prime is 20664601. The next prime is 20664641. The reversal of 20664609 is 90646602.

It is not a de Polignac number, because 20664609 - 2³ = 20664601 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20664609.

It is not an unprimeable number, because it can be changed into a prime (20664601) 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 31 ways as a sum of consecutive naturals, for example, 26347 + ... + 27119.

It is an arithmetic number, because the mean of its divisors is an integer number (1052640).

Almost surely, 2^20664609 is an apocalyptic number.

It is an amenable number.

20664609 is a deficient number, since it is larger than the sum of its proper divisors (13019871).

20664609 is a wasteful number, since it uses less digits than its factorization.

20664609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869.

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 20664609 is about 4545.8342468682. The cubic root of 20664609 is about 274.4157690607.

The spelling of 20664609 in words is "twenty million, six hundred sixty-four thousand, six hundred nine".