21866001666 has 64 divisors (see below), whose sum is σ = 46325952000. Its totient is φ = 6871737600.

The previous prime is 21866001631. The next prime is 21866001671. The reversal of 21866001666 is 66610066812.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1043460 + ... + 1064208.

It is an arithmetic number, because the mean of its divisors is an integer number (723843000).

Almost surely, 2^21866001666 is an apocalyptic number.

21866001666 is an abundant number, since it is smaller than the sum of its proper divisors (24459950334).

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

21866001666 is a wasteful number, since it uses less digits than its factorization.

21866001666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20939.

The product of its (nonzero) digits is 124416, while the sum is 42.

The spelling of 21866001666 in words is "twenty-one billion, eight hundred sixty-six million, one thousand, six hundred sixty-six".