18109505 has 16 divisors (see below), whose sum is σ = 23127120. Its totient is φ = 13565952.

The previous prime is 18109501. The next prime is 18109547. The reversal of 18109505 is 50590181.

It can be written as a sum of positive squares in 8 ways, for example, as 3356224 + 14753281 = 1832^2 + 3841^2 .

It is a cyclic number.

It is not a de Polignac number, because 18109505 - 2² = 18109501 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18109501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21431 + ... + 22259.

It is an arithmetic number, because the mean of its divisors is an integer number (1445445).

Almost surely, 2^18109505 is an apocalyptic number.

It is an amenable number.

18109505 is a deficient number, since it is larger than the sum of its proper divisors (5017615).

18109505 is a wasteful number, since it uses less digits than its factorization.

18109505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1108.

The product of its (nonzero) digits is 1800, while the sum is 29.

The square root of 18109505 is about 4255.5264069208. The cubic root of 18109505 is about 262.6045177143.

Adding to 18109505 its reverse (50590181), we get a palindrome (68699686).

The spelling of 18109505 in words is "eighteen million, one hundred nine thousand, five hundred five".