16328221 has 12 divisors (see below), whose sum is σ = 20455932. Its totient is φ = 12918528.

The previous prime is 16328219. The next prime is 16328231. The reversal of 16328221 is 12282361.

It can be written as a sum of positive squares in 2 ways, for example, as 3980025 + 12348196 = 1995^2 + 3514^2 .

It is not a de Polignac number, because 16328221 - 2¹ = 16328219 is a prime.

It is a super-2 number, since 2×16328221² = 533221602049682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16328231) 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 11 ways as a sum of consecutive naturals, for example, 12180 + ... + 13453.

It is an arithmetic number, because the mean of its divisors is an integer number (1704661).

Almost surely, 2^16328221 is an apocalyptic number.

It is an amenable number.

16328221 is a deficient number, since it is larger than the sum of its proper divisors (4127711).

16328221 is a wasteful number, since it uses less digits than its factorization.

16328221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25660 (or 25653 counting only the distinct ones).

The product of its digits is 1152, while the sum is 25.

The square root of 16328221 is about 4040.8193476076. The cubic root of 16328221 is about 253.6956126006.

The spelling of 16328221 in words is "sixteen million, three hundred twenty-eight thousand, two hundred twenty-one".