21666618886 has 12 divisors (see below), whose sum is σ = 35723062116. Its totient is φ = 9848463020.

The previous prime is 21666618811. The next prime is 21666618887. The reversal of 21666618886 is 68881666612.

It is a self number, because there is not a number n which added to its sum of digits gives 21666618886.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666618887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 44765500 + ... + 44765983.

It is an arithmetic number, because the mean of its divisors is an integer number (2976921843).

Almost surely, 2^21666618886 is an apocalyptic number.

21666618886 is a deficient number, since it is larger than the sum of its proper divisors (14056443230).

21666618886 is a wasteful number, since it uses less digits than its factorization.

21666618886 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89531507 (or 89531496 counting only the distinct ones).

The product of its digits is 7962624, while the sum is 58.

The spelling of 21666618886 in words is "twenty-one billion, six hundred sixty-six million, six hundred eighteen thousand, eight hundred eighty-six".