21667456664 has 32 divisors (see below), whose sum is σ = 48873964800. Its totient is φ = 8797312800.

The previous prime is 21667456579. The next prime is 21667456667. The reversal of 21667456664 is 46665476612.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21667456667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10181012 + ... + 10183139.

It is an arithmetic number, because the mean of its divisors is an integer number (1527311400).

Almost surely, 2^21667456664 is an apocalyptic number.

It is an amenable number.

21667456664 is an abundant number, since it is smaller than the sum of its proper divisors (27206508136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21667456664 is a wasteful number, since it uses less digits than its factorization.

21667456664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20364183 (or 20364179 counting only the distinct ones).

The product of its digits is 8709120, while the sum is 53.

The spelling of 21667456664 in words is "twenty-one billion, six hundred sixty-seven million, four hundred fifty-six thousand, six hundred sixty-four".