18505665 has 28 divisors (see below), whose sum is σ = 33301524. Its totient is φ = 9867744.

The previous prime is 18505657. The next prime is 18505679. The reversal of 18505665 is 56650581.

It can be written as a sum of positive squares in 2 ways, for example, as 13483584 + 5022081 = 3672^2 + 2241^2 .

It is not a de Polignac number, because 18505665 - 2³ = 18505657 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 1107 + ... + 6183.

Almost surely, 2^18505665 is an apocalyptic number.

18505665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18505665 is a deficient number, since it is larger than the sum of its proper divisors (14795859).

18505665 is an frugal number, since it uses more digits than its factorization.

18505665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5100 (or 5085 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 36.

The square root of 18505665 is about 4301.8211259884. The cubic root of 18505665 is about 264.5056167608.

The spelling of 18505665 in words is "eighteen million, five hundred five thousand, six hundred sixty-five".