20686685 has 4 divisors (see below), whose sum is σ = 24824028. Its totient is φ = 16549344.

The previous prime is 20686681. The next prime is 20686691. The reversal of 20686685 is 58668602.

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 3728761 + 16957924 = 1931^2 + 4118^2 .

It is a cyclic number.

It is not a de Polignac number, because 20686685 - 2² = 20686681 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20686681) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2068664 + ... + 2068673.

It is an arithmetic number, because the mean of its divisors is an integer number (6206007).

Almost surely, 2^20686685 is an apocalyptic number.

It is an amenable number.

20686685 is a deficient number, since it is larger than the sum of its proper divisors (4137343).

20686685 is an equidigital number, since it uses as much as digits as its factorization.

20686685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4137342.

The product of its (nonzero) digits is 138240, while the sum is 41.

The square root of 20686685 is about 4548.2617558799. The cubic root of 20686685 is about 274.5134537308.

The spelling of 20686685 in words is "twenty million, six hundred eighty-six thousand, six hundred eighty-five".