21305331668 has 24 divisors (see below), whose sum is σ = 39482917992. Its totient is φ = 10024669184.

The previous prime is 21305331667. The next prime is 21305331673. The reversal of 21305331668 is 86613350312.

It can be written as a sum of positive squares in 4 ways, for example, as 7112898244 + 14192433424 = 84338^2 + 119132^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305331667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 620930 + ... + 654342.

It is an arithmetic number, because the mean of its divisors is an integer number (1645121583).

Almost surely, 2^21305331668 is an apocalyptic number.

It is an amenable number.

21305331668 is a deficient number, since it is larger than the sum of its proper divisors (18177586324).

21305331668 is a wasteful number, since it uses less digits than its factorization.

21305331668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42811 (or 42809 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 38.

The spelling of 21305331668 in words is "twenty-one billion, three hundred five million, three hundred thirty-one thousand, six hundred sixty-eight".