20686583809 has 4 divisors (see below), whose sum is σ = 20694268116. Its totient is φ = 20678899504.

The previous prime is 20686583803. The next prime is 20686583843. The reversal of 20686583809 is 90838568602.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90838568602 = 2 ⋅45419284301.

It can be written as a sum of positive squares in 2 ways, for example, as 11459060209 + 9227523600 = 107047^2 + 96060^2 .

It is a cyclic number.

It is not a de Polignac number, because 20686583809 - 2⁵ = 20686583777 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20686583809.

It is not an unprimeable number, because it can be changed into a prime (20686583803) 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, 3838114 + ... + 3843499.

It is an arithmetic number, because the mean of its divisors is an integer number (5173567029).

Almost surely, 2^20686583809 is an apocalyptic number.

It is an amenable number.

20686583809 is a deficient number, since it is larger than the sum of its proper divisors (7684307).

20686583809 is an equidigital number, since it uses as much as digits as its factorization.

20686583809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7684306.

The product of its (nonzero) digits is 4976640, while the sum is 55.

The spelling of 20686583809 in words is "twenty billion, six hundred eighty-six million, five hundred eighty-three thousand, eight hundred nine".