21641005566 has 24 divisors (see below), whose sum is σ = 46896239520. Its totient is φ = 7212530976.

The previous prime is 21641005549. The next prime is 21641005579. The reversal of 21641005566 is 66550014612.

21641005566 is a `hidden beast` number, since 2 + 1 + 641 + 0 + 0 + 5 + 5 + 6 + 6 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21641005566.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26731 + ... + 209753.

It is an arithmetic number, because the mean of its divisors is an integer number (1954009980).

Almost surely, 2^21641005566 is an apocalyptic number.

21641005566 is an abundant number, since it is smaller than the sum of its proper divisors (25255233954).

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

21641005566 is a wasteful number, since it uses less digits than its factorization.

21641005566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189600 (or 189597 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The spelling of 21641005566 in words is "twenty-one billion, six hundred forty-one million, five thousand, five hundred sixty-six".