21643378566552 has 64 divisors (see below), whose sum is σ = 60127309209600. Its totient is φ = 7213641939360.

The previous prime is 21643378566443. The next prime is 21643378566559. The reversal of 21643378566552 is 25566587334612.

21643378566552 is a `hidden beast` number, since 2 + 1 + 6 + 4 + 3 + 3 + 78 + 5 + 6 + 6 + 552 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21643378566552.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643378566559) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3765748 + ... + 7580739.

It is an arithmetic number, because the mean of its divisors is an integer number (939489206400).

Almost surely, 2^{21643378566552} is an apocalyptic number.

It is an amenable number.

21643378566552 is an abundant number, since it is smaller than the sum of its proper divisors (38483930643048).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21643378566552 is a wasteful number, since it uses less digits than its factorization.

21643378566552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11355333 (or 11355323 counting only the distinct ones).

The product of its digits is 217728000, while the sum is 63.

The spelling of 21643378566552 in words is "twenty-one trillion, six hundred forty-three billion, three hundred seventy-eight million, five hundred sixty-six thousand, five hundred fifty-two".