20640164 has 6 divisors (see below), whose sum is σ = 36120294. Its totient is φ = 10320080.

The previous prime is 20640163. The next prime is 20640181. The reversal of 20640164 is 46104602.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20430400 + 209764 = 4520^2 + 458^2 .

It is not an unprimeable number, because it can be changed into a prime (20640163) 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 as a sum of consecutive naturals, namely, 2580017 + ... + 2580024.

It is an arithmetic number, because the mean of its divisors is an integer number (6020049).

Almost surely, 2^20640164 is an apocalyptic number.

It is an amenable number.

20640164 is a deficient number, since it is larger than the sum of its proper divisors (15480130).

20640164 is a wasteful number, since it uses less digits than its factorization.

20640164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5160045 (or 5160043 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 20640164 is about 4543.1447258479. The cubic root of 20640164 is about 274.3075205361.

Adding to 20640164 its reverse (46104602), we get a palindrome (66744766).

The spelling of 20640164 in words is "twenty million, six hundred forty thousand, one hundred sixty-four".