18115409 has 4 divisors (see below), whose sum is σ = 19508916. Its totient is φ = 16721904.

The previous prime is 18115403. The next prime is 18115441. The reversal of 18115409 is 90451181.

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 1890625 + 16224784 = 1375^2 + 4028^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18115409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18115403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 696734 + ... + 696759.

It is an arithmetic number, because the mean of its divisors is an integer number (4877229).

Almost surely, 2^18115409 is an apocalyptic number.

It is an amenable number.

18115409 is a deficient number, since it is larger than the sum of its proper divisors (1393507).

18115409 is a wasteful number, since it uses less digits than its factorization.

18115409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1393506.

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 18115409 is about 4256.2200366053. The cubic root of 18115409 is about 262.6330524279.

The spelling of 18115409 in words is "eighteen million, one hundred fifteen thousand, four hundred nine".