21665665020404 has 12 divisors (see below), whose sum is σ = 38156410052964. Its totient is φ = 10763833576704.

The previous prime is 21665665020383. The next prime is 21665665020457. The reversal of 21665665020404 is 40402056656612.

It can be written as a sum of positive squares in 2 ways, for example, as 14579048335504 + 7086616684900 = 3818252^2 + 2662070^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17249732669 + ... + 17249733924.

It is an arithmetic number, because the mean of its divisors is an integer number (3179700837747).

Almost surely, 2^{21665665020404} is an apocalyptic number.

It is an amenable number.

21665665020404 is a deficient number, since it is larger than the sum of its proper divisors (16490745032560).

21665665020404 is a wasteful number, since it uses less digits than its factorization.

21665665020404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34499466754 (or 34499466752 counting only the distinct ones).

The product of its (nonzero) digits is 2073600, while the sum is 47.

The spelling of 21665665020404 in words is "twenty-one trillion, six hundred sixty-five billion, six hundred sixty-five million, twenty thousand, four hundred four".