16664321 has 2 divisors, whose sum is σ = 16664322. Its totient is φ = 16664320.

The previous prime is 16664317. The next prime is 16664341. The reversal of 16664321 is 12346661.

It is a happy number.

16664321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16516096 + 148225 = 4064^2 + 385^2 .

It is an emirp because it is prime and its reverse (12346661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16664321 - 2² = 16664317 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (16664341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8332160 + 8332161.

It is an arithmetic number, because the mean of its divisors is an integer number (8332161).

Almost surely, 2^16664321 is an apocalyptic number.

It is an amenable number.

16664321 is a deficient number, since it is larger than the sum of its proper divisors (1).

16664321 is an equidigital number, since it uses as much as digits as its factorization.

16664321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 29.

The square root of 16664321 is about 4082.1956102078. The cubic root of 16664321 is about 255.4244935257.

The spelling of 16664321 in words is "sixteen million, six hundred sixty-four thousand, three hundred twenty-one".