21456378672544 has 24 divisors (see below), whose sum is σ = 42426709480260. Its totient is φ = 10681341344256.

The previous prime is 21456378672529. The next prime is 21456378672557. The reversal of 21456378672544 is 44527687365412.

It can be written as a sum of positive squares in 2 ways, for example, as 21371574243600 + 84804428944 = 4622940^2 + 291212^2 .

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, 1463992309 + ... + 1464006964.

Almost surely, 2^{21456378672544} is an apocalyptic number.

It is an amenable number.

21456378672544 is a deficient number, since it is larger than the sum of its proper divisors (20970330807716).

21456378672544 is a wasteful number, since it uses less digits than its factorization.

21456378672544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2927999512 (or 2927999504 counting only the distinct ones).

The product of its digits is 270950400, while the sum is 64.

The spelling of 21456378672544 in words is "twenty-one trillion, four hundred fifty-six billion, three hundred seventy-eight million, six hundred seventy-two thousand, five hundred forty-four".