21105664704 has 84 divisors (see below), whose sum is σ = 60594645384. Its totient is φ = 7023700992.

The previous prime is 21105664703. The next prime is 21105664763. The reversal of 21105664704 is 40746650112.

21105664704 is a `hidden beast` number, since 2 + 1 + 1 + 0 + 5 + 6 + 647 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21105664703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 325699 + ... + 385085.

It is an arithmetic number, because the mean of its divisors is an integer number (721364826).

Almost surely, 2^21105664704 is an apocalyptic number.

21105664704 is a gapful number since it is divisible by the number (24) 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 21105664704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30297322692).

21105664704 is an abundant number, since it is smaller than the sum of its proper divisors (39488980680).

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

21105664704 is a wasteful number, since it uses less digits than its factorization.

21105664704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60022 (or 60009 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 21105664704 in words is "twenty-one billion, one hundred five million, six hundred sixty-four thousand, seven hundred four".