16404321 has 4 divisors (see below), whose sum is σ = 21872432. Its totient is φ = 10936212.

The previous prime is 16404307. The next prime is 16404329. The reversal of 16404321 is 12340461.

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 not a de Polignac number, because 16404321 - 2⁹ = 16403809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16404329) 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, 2734051 + ... + 2734056.

It is an arithmetic number, because the mean of its divisors is an integer number (5468108).

Almost surely, 2^16404321 is an apocalyptic number.

It is an amenable number.

16404321 is a deficient number, since it is larger than the sum of its proper divisors (5468111).

16404321 is an equidigital number, since it uses as much as digits as its factorization.

16404321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5468110.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 16404321 is about 4050.2248085754. The cubic root of 16404321 is about 254.0891300651.

Adding to 16404321 its reverse (12340461), we get a palindrome (28744782).

The spelling of 16404321 in words is "sixteen million, four hundred four thousand, three hundred twenty-one".