20665984 has 16 divisors (see below), whose sum is σ = 41170770. Its totient is φ = 10332928.

The previous prime is 20665979. The next prime is 20665987. The reversal of 20665984 is 48956602.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13483584 + 7182400 = 3672^2 + 2680^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is not an unprimeable number, because it can be changed into a prime (20665987) 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 as a sum of consecutive naturals, namely, 80599 + ... + 80854.

Almost surely, 2^20665984 is an apocalyptic number.

It is an amenable number.

20665984 is a deficient number, since it is larger than the sum of its proper divisors (20504786).

20665984 is an equidigital number, since it uses as much as digits as its factorization.

20665984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161467 (or 161455 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 40.

The square root of 20665984 is about 4545.9854817190. The cubic root of 20665984 is about 274.4218553652.

It can be divided in two parts, 2066598 and 4, that added together give a palindrome (2066602).

The spelling of 20665984 in words is "twenty million, six hundred sixty-five thousand, nine hundred eighty-four".