21166311668 has 12 divisors (see below), whose sum is σ = 37050303780. Its totient is φ = 10580510592.

The previous prime is 21166311659. The next prime is 21166311707. The reversal of 21166311668 is 86611366112.

It can be written as a sum of positive squares in 2 ways, for example, as 18031655524 + 3134656144 = 134282^2 + 55988^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 643253 + ... + 675356.

It is an arithmetic number, because the mean of its divisors is an integer number (3087525315).

Almost surely, 2^21166311668 is an apocalyptic number.

It is an amenable number.

21166311668 is a deficient number, since it is larger than the sum of its proper divisors (15883992112).

21166311668 is a wasteful number, since it uses less digits than its factorization.

21166311668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1322626 (or 1322624 counting only the distinct ones).

The product of its digits is 62208, while the sum is 41.

The spelling of 21166311668 in words is "twenty-one billion, one hundred sixty-six million, three hundred eleven thousand, six hundred sixty-eight".