21664101888 has 600 divisors, whose sum is σ = 76655345976. Its totient is φ = 6038323200.

The previous prime is 21664101883. The next prime is 21664101923. The reversal of 21664101888 is 88810146612.

21664101888 is a `hidden beast` number, since 216 + 6 + 410 + 18 + 8 + 8 = 666.

It is a super-2 number, since 2×21664101888² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664101881) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 77096308 + ... + 77096588.

Almost surely, 2^21664101888 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21664101888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38327672988).

21664101888 is an abundant number, since it is smaller than the sum of its proper divisors (54991244088).

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

21664101888 is a wasteful number, since it uses less digits than its factorization.

21664101888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 348 (or 310 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 45.

The spelling of 21664101888 in words is "twenty-one billion, six hundred sixty-four million, one hundred one thousand, eight hundred eighty-eight".