21661042106564 has 24 divisors (see below), whose sum is σ = 43322733863808. Its totient is φ = 9283164549120.

The previous prime is 21661042106551. The next prime is 21661042106581. The reversal of 21661042106564 is 46560124016612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3888872 + ... + 7644959.

It is an arithmetic number, because the mean of its divisors is an integer number (1805113910992).

Almost surely, 2^{21661042106564} is an apocalyptic number.

It is an amenable number.

21661042106564 is an abundant number, since it is smaller than the sum of its proper divisors (21661691757244).

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

21661042106564 is a wasteful number, since it uses less digits than its factorization.

21661042106564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11600915 (or 11600913 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 44.

The spelling of 21661042106564 in words is "twenty-one trillion, six hundred sixty-one billion, forty-two million, one hundred six thousand, five hundred sixty-four".