16405321 has 4 divisors (see below), whose sum is σ = 16435332. Its totient is φ = 16375312.

The previous prime is 16405313. The next prime is 16405343. The reversal of 16405321 is 12350461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12350461 = 149 ⋅82889.

It can be written as a sum of positive squares in 2 ways, for example, as 4260096 + 12145225 = 2064^2 + 3485^2 .

It is a cyclic number.

It is not a de Polignac number, because 16405321 - 2³ = 16405313 is a prime.

It is a super-2 number, since 2×16405321² = 538269114226082, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16405292 and 16405301.

It is not an unprimeable number, because it can be changed into a prime (16405351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14170 + ... + 15283.

It is an arithmetic number, because the mean of its divisors is an integer number (4108833).

Almost surely, 2^16405321 is an apocalyptic number.

It is an amenable number.

16405321 is a deficient number, since it is larger than the sum of its proper divisors (30011).

16405321 is an equidigital number, since it uses as much as digits as its factorization.

16405321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30010.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 16405321 is about 4050.3482566318. The cubic root of 16405321 is about 254.0942930130.

Adding to 16405321 its reverse (12350461), we get a palindrome (28755782).

The spelling of 16405321 in words is "sixteen million, four hundred five thousand, three hundred twenty-one".