20556685 has 4 divisors (see below), whose sum is σ = 24668028. Its totient is φ = 16445344.

The previous prime is 20556673. The next prime is 20556691. The reversal of 20556685 is 58665502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15038884 + 5517801 = 3878^2 + 2349^2 .

It is a cyclic number.

It is not a de Polignac number, because 20556685 - 2²³ = 12168077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2055664 + ... + 2055673.

It is an arithmetic number, because the mean of its divisors is an integer number (6167007).

Almost surely, 2^20556685 is an apocalyptic number.

It is an amenable number.

20556685 is a deficient number, since it is larger than the sum of its proper divisors (4111343).

20556685 is an equidigital number, since it uses as much as digits as its factorization.

20556685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4111342.

The product of its (nonzero) digits is 72000, while the sum is 37.

The square root of 20556685 is about 4533.9480588114. The cubic root of 20556685 is about 273.9372092252.

The spelling of 20556685 in words is "twenty million, five hundred fifty-six thousand, six hundred eighty-five".