21008404668 has 12 divisors (see below), whose sum is σ = 49019610920. Its totient is φ = 7002801552.

The previous prime is 21008404661. The next prime is 21008404673. The reversal of 21008404668 is 86640480012.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008404661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 875350183 + ... + 875350206.

Almost surely, 2^21008404668 is an apocalyptic number.

It is an amenable number.

21008404668 is an abundant number, since it is smaller than the sum of its proper divisors (28011206252).

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

21008404668 is a wasteful number, since it uses less digits than its factorization.

21008404668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1750700396 (or 1750700394 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 39.

The spelling of 21008404668 in words is "twenty-one billion, eight million, four hundred four thousand, six hundred sixty-eight".