16644321 has 12 divisors (see below), whose sum is σ = 24150672. Its totient is φ = 11045976.

The previous prime is 16644301. The next prime is 16644337. The reversal of 16644321 is 12344661.

16644321 is a `hidden beast` number, since 16 + 644 + 3 + 2 + 1 = 666.

It is not a de Polignac number, because 16644321 - 2⁷ = 16644193 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16644301) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2031 + ... + 6116.

It is an arithmetic number, because the mean of its divisors is an integer number (2012556).

Almost surely, 2^16644321 is an apocalyptic number.

It is an amenable number.

16644321 is a deficient number, since it is larger than the sum of its proper divisors (7506351).

16644321 is a wasteful number, since it uses less digits than its factorization.

16644321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8380 (or 8377 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 16644321 is about 4079.7452126328. The cubic root of 16644321 is about 255.3222684402.

Adding to 16644321 its reverse (12344661), we get a palindrome (28988982).

It can be divided in two parts, 166443 and 21, that added together give a square (166464 = 408²).

The spelling of 16644321 in words is "sixteen million, six hundred forty-four thousand, three hundred twenty-one".