21664213304 has 32 divisors (see below), whose sum is σ = 41710032000. Its totient is φ = 10545104352.

The previous prime is 21664213297. The next prime is 21664213309. The reversal of 21664213304 is 40331246612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664213309) 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, 174194 + ... + 271425.

It is an arithmetic number, because the mean of its divisors is an integer number (1303438500).

Almost surely, 2^21664213304 is an apocalyptic number.

It is an amenable number.

21664213304 is a deficient number, since it is larger than the sum of its proper divisors (20045818696).

21664213304 is a wasteful number, since it uses less digits than its factorization.

21664213304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445787 (or 445783 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 32.

Adding to 21664213304 its reverse (40331246612), we get a palindrome (61995459916).

The spelling of 21664213304 in words is "twenty-one billion, six hundred sixty-four million, two hundred thirteen thousand, three hundred four".