20218664 has 32 divisors (see below), whose sum is σ = 38961000. Its totient is φ = 9833472.

The previous prime is 20218637. The next prime is 20218669. The reversal of 20218664 is 46681202.

It can be written as a sum of positive squares in 4 ways, for example, as 12545764 + 7672900 = 3542^2 + 2770^2 .

It is not an unprimeable number, because it can be changed into a prime (20218669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51782 + ... + 52170.

Almost surely, 2^20218664 is an apocalyptic number.

It is an amenable number.

20218664 is a deficient number, since it is larger than the sum of its proper divisors (18742336).

20218664 is a wasteful number, since it uses less digits than its factorization.

20218664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557 (or 553 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 20218664 is about 4496.5168742039. The cubic root of 20218664 is about 272.4274205605.

Adding to 20218664 its reverse (46681202), we get a palindrome (66899866).

The spelling of 20218664 in words is "twenty million, two hundred eighteen thousand, six hundred sixty-four".