21611969568 has 144 divisors (see below), whose sum is σ = 70896047040. Its totient is φ = 6117078528.

The previous prime is 21611969557. The next prime is 21611969609. The reversal of 21611969568 is 86596911612.

21611969568 is a `hidden beast` number, since 2 + 1 + 6 + 1 + 19 + 69 + 568 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 165618 + ... + 265806.

It is an arithmetic number, because the mean of its divisors is an integer number (492333660).

Almost surely, 2^21611969568 is an apocalyptic number.

21611969568 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 21611969568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35448023520).

21611969568 is an abundant number, since it is smaller than the sum of its proper divisors (49284077472).

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

21611969568 is a wasteful number, since it uses less digits than its factorization.

21611969568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100319 (or 100308 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 54.

The spelling of 21611969568 in words is "twenty-one billion, six hundred eleven million, nine hundred sixty-nine thousand, five hundred sixty-eight".