21055605666 has 64 divisors (see below), whose sum is σ = 44305121280. Its totient is φ = 6662710080.

The previous prime is 21055605601. The next prime is 21055605667. The reversal of 21055605666 is 66650655012.

It is not an unprimeable number, because it can be changed into a prime (21055605667) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2302395 + ... + 2311521.

It is an arithmetic number, because the mean of its divisors is an integer number (692267520).

Almost surely, 2^21055605666 is an apocalyptic number.

21055605666 is an abundant number, since it is smaller than the sum of its proper divisors (23249515614).

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

21055605666 is a wasteful number, since it uses less digits than its factorization.

21055605666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9399.

The product of its (nonzero) digits is 324000, while the sum is 42.

The spelling of 21055605666 in words is "twenty-one billion, fifty-five million, six hundred five thousand, six hundred sixty-six".