18238321 has 4 divisors (see below), whose sum is σ = 18662512. Its totient is φ = 17814132.

The previous prime is 18238301. The next prime is 18238349. The reversal of 18238321 is 12383281.

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: 12383281 = 401 ⋅30881.

It is a cyclic number.

It is not a de Polignac number, because 18238321 - 2⁵ = 18238289 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18238321.

It is not an unprimeable number, because it can be changed into a prime (18238301) 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, 212031 + ... + 212116.

It is an arithmetic number, because the mean of its divisors is an integer number (4665628).

Almost surely, 2^18238321 is an apocalyptic number.

It is an amenable number.

18238321 is a deficient number, since it is larger than the sum of its proper divisors (424191).

18238321 is an equidigital number, since it uses as much as digits as its factorization.

18238321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 424190.

The product of its digits is 2304, while the sum is 28.

The square root of 18238321 is about 4270.6347303416. The cubic root of 18238321 is about 263.2256974337.

It can be divided in two parts, 182 and 38321, that added together give a triangular number (38503 = T₂₇₇).

The spelling of 18238321 in words is "eighteen million, two hundred thirty-eight thousand, three hundred twenty-one".