18321109 has 4 divisors (see below), whose sum is σ = 18329740. Its totient is φ = 18312480.

The previous prime is 18321103. The next prime is 18321113. The reversal of 18321109 is 90112381.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90112381 = 31 ⋅2906851.

It can be written as a sum of positive squares in 2 ways, for example, as 16080100 + 2241009 = 4010^2 + 1497^2 .

It is a cyclic number.

It is not a de Polignac number, because 18321109 - 2³ = 18321101 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 (18321101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1339 + ... + 6199.

It is an arithmetic number, because the mean of its divisors is an integer number (4582435).

Almost surely, 2^18321109 is an apocalyptic number.

It is an amenable number.

18321109 is a deficient number, since it is larger than the sum of its proper divisors (8631).

18321109 is an equidigital number, since it uses as much as digits as its factorization.

18321109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8630.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 18321109 is about 4280.3164602632. The cubic root of 18321109 is about 263.6233772978.

The spelling of 18321109 in words is "eighteen million, three hundred twenty-one thousand, one hundred nine".