20809986 has 16 divisors (see below), whose sum is σ = 43429824. Its totient is φ = 6635024.

The previous prime is 20809961. The next prime is 20809991. The reversal of 20809986 is 68990802.

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, 75261 + ... + 75536.

It is an arithmetic number, because the mean of its divisors is an integer number (2714364).

Almost surely, 2^20809986 is an apocalyptic number.

20809986 is an abundant number, since it is smaller than the sum of its proper divisors (22619838).

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

20809986 is a wasteful number, since it uses less digits than its factorization.

20809986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150825.

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 20809986 is about 4561.7963566998. The cubic root of 20809986 is about 275.0577773918.

The spelling of 20809986 in words is "twenty million, eight hundred nine thousand, nine hundred eighty-six".