18400321 has 4 divisors (see below), whose sum is σ = 18438592. Its totient is φ = 18362052.

The previous prime is 18400313. The next prime is 18400351. The reversal of 18400321 is 12300481.

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.

It is a cyclic number.

It is not a de Polignac number, because 18400321 - 2³ = 18400313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18400301) 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, 18405 + ... + 19378.

It is an arithmetic number, because the mean of its divisors is an integer number (4609648).

Almost surely, 2^18400321 is an apocalyptic number.

It is an amenable number.

18400321 is a deficient number, since it is larger than the sum of its proper divisors (38271).

18400321 is an equidigital number, since it uses as much as digits as its factorization.

18400321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38270.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 18400321 is about 4289.5595344977. The cubic root of 18400321 is about 264.0027595748.

It can be divided in two parts, 18400 and 321, that added together give a triangular number (18721 = T₁₉₃).

The spelling of 18400321 in words is "eighteen million, four hundred thousand, three hundred twenty-one".