18531109 has 4 divisors (see below), whose sum is σ = 18765760. Its totient is φ = 18296460.

The previous prime is 18531091. The next prime is 18531119. The reversal of 18531109 is 90113581.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90113581 = 107 ⋅842183.

It is a cyclic number.

It is not a de Polignac number, because 18531109 - 2⁹ = 18530597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18531119) 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, 117207 + ... + 117364.

It is an arithmetic number, because the mean of its divisors is an integer number (4691440).

Almost surely, 2^18531109 is an apocalyptic number.

It is an amenable number.

18531109 is a deficient number, since it is larger than the sum of its proper divisors (234651).

18531109 is an equidigital number, since it uses as much as digits as its factorization.

18531109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234650.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 18531109 is about 4304.7774623086. Note that the first 3 decimals coincide. The cubic root of 18531109 is about 264.6267868422.

The spelling of 18531109 in words is "eighteen million, five hundred thirty-one thousand, one hundred nine".