21556665512 has 16 divisors (see below), whose sum is σ = 40435632000. Its totient is φ = 10773830320.

The previous prime is 21556665413. The next prime is 21556665539.

21556665512 is nontrivially palindromic in base 10.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542414 + ... + 580797.

It is an arithmetic number, because the mean of its divisors is an integer number (2527227000).

Almost surely, 2^21556665512 is an apocalyptic number.

It is an amenable number.

21556665512 is a deficient number, since it is larger than the sum of its proper divisors (18878966488).

21556665512 is a wasteful number, since it uses less digits than its factorization.

21556665512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1125616 (or 1125612 counting only the distinct ones).

The product of its digits is 540000, while the sum is 44.

The spelling of 21556665512 in words is "twenty-one billion, five hundred fifty-six million, six hundred sixty-five thousand, five hundred twelve".