21668477388 has 96 divisors (see below), whose sum is σ = 53150247360. Its totient is φ = 6863201280.

The previous prime is 21668477359. The next prime is 21668477393. The reversal of 21668477388 is 88377486612.

It is a happy number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 5386818 + ... + 5390838.

It is an arithmetic number, because the mean of its divisors is an integer number (553648410).

Almost surely, 2^21668477388 is an apocalyptic number.

It is an amenable number.

21668477388 is an abundant number, since it is smaller than the sum of its proper divisors (31481769972).

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

21668477388 is a wasteful number, since it uses less digits than its factorization.

21668477388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4347 (or 4345 counting only the distinct ones).

The product of its digits is 21676032, while the sum is 60.

The spelling of 21668477388 in words is "twenty-one billion, six hundred sixty-eight million, four hundred seventy-seven thousand, three hundred eighty-eight".