20856666 has 16 divisors (see below), whose sum is σ = 42501024. Its totient is φ = 6820944.

The previous prime is 20856629. The next prime is 20856679. The reversal of 20856666 is 66665802.

20856666 is nontrivially palindromic in base 12.

It is a Curzon number.

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, 32476 + ... + 33111.

It is an arithmetic number, because the mean of its divisors is an integer number (2656314).

Almost surely, 2^20856666 is an apocalyptic number.

20856666 is an abundant number, since it is smaller than the sum of its proper divisors (21644358).

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

20856666 is a wasteful number, since it uses less digits than its factorization.

20856666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65645.

The product of its (nonzero) digits is 103680, while the sum is 39.

The square root of 20856666 is about 4566.9098961990. The cubic root of 20856666 is about 275.2632894398.

The spelling of 20856666 in words is "twenty million, eight hundred fifty-six thousand, six hundred sixty-six".