21664147008 has 224 divisors, whose sum is σ = 68300559360. Its totient is φ = 5929297920.

The previous prime is 21664146991. The next prime is 21664147031. The reversal of 21664147008 is 80074146612.

It is a tau number, because it is divible by the number of its divisors (224).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5103735 + ... + 5107977.

Almost surely, 2^21664147008 is an apocalyptic number.

21664147008 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21664147008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34150279680).

21664147008 is an abundant number, since it is smaller than the sum of its proper divisors (46636412352).

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

21664147008 is a wasteful number, since it uses less digits than its factorization.

21664147008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4425 (or 4415 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 39.

The spelling of 21664147008 in words is "twenty-one billion, six hundred sixty-four million, one hundred forty-seven thousand, eight".