21104644566 has 32 divisors (see below), whose sum is σ = 45465274368. Its totient is φ = 6511950720.

The previous prime is 21104644471. The next prime is 21104644579. The reversal of 21104644566 is 66544640112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2462371 + ... + 2470926.

It is an arithmetic number, because the mean of its divisors is an integer number (1420789824).

Almost surely, 2^21104644566 is an apocalyptic number.

21104644566 is an abundant number, since it is smaller than the sum of its proper divisors (24360629802).

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

21104644566 is a wasteful number, since it uses less digits than its factorization.

21104644566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4933356.

The product of its (nonzero) digits is 138240, while the sum is 39.

It can be divided in two parts, 2110 and 4644566, that added together give a triangular number (4646676 = T₃₀₄₈).

The spelling of 21104644566 in words is "twenty-one billion, one hundred four million, six hundred forty-four thousand, five hundred sixty-six".