16663321 has 2 divisors, whose sum is σ = 16663322. Its totient is φ = 16663320.

The previous prime is 16663307. The next prime is 16663351. The reversal of 16663321 is 12336661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8761600 + 7901721 = 2960^2 + 2811^2 .

It is an emirp because it is prime and its reverse (12336661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16663321 - 2⁹ = 16662809 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16663321.

It is not a weakly prime, because it can be changed into another prime (16663301) 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 as a sum of consecutive naturals, namely, 8331660 + 8331661.

It is an arithmetic number, because the mean of its divisors is an integer number (8331661).

Almost surely, 2^16663321 is an apocalyptic number.

It is an amenable number.

16663321 is a deficient number, since it is larger than the sum of its proper divisors (1).

16663321 is an equidigital number, since it uses as much as digits as its factorization.

16663321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 28.

The square root of 16663321 is about 4082.0731252637. The cubic root of 16663321 is about 255.4193842145.

Adding to 16663321 its reverse (12336661), we get a palindrome (28999982).

The spelling of 16663321 in words is "sixteen million, six hundred sixty-three thousand, three hundred twenty-one".