20685486665 has 12 divisors (see below), whose sum is σ = 25442789772. Its totient is φ = 16144763520.

The previous prime is 20685486643. The next prime is 20685486739. The reversal of 20685486665 is 56668458602.

It can be written as a sum of positive squares in 6 ways, for example, as 2907797776 + 17777688889 = 53924^2 + 133333^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20685486665 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 20685486665.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1222142 + ... + 1238951.

It is an arithmetic number, because the mean of its divisors is an integer number (2120232481).

Almost surely, 2^20685486665 is an apocalyptic number.

It is an amenable number.

20685486665 is a deficient number, since it is larger than the sum of its proper divisors (4757303107).

20685486665 is an equidigital number, since it uses as much as digits as its factorization.

20685486665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2461180 (or 2461139 counting only the distinct ones).

The product of its (nonzero) digits is 16588800, while the sum is 56.

The spelling of 20685486665 in words is "twenty billion, six hundred eighty-five million, four hundred eighty-six thousand, six hundred sixty-five".