666533321 has 2 divisors, whose sum is σ = 666533322. Its totient is φ = 666533320.

The previous prime is 666533317. The next prime is 666533323. The reversal of 666533321 is 123335666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 624750025 + 41783296 = 24995^2 + 6464^2 .

It is a cyclic number.

It is not a de Polignac number, because 666533321 - 2² = 666533317 is a prime.

It is a Sophie Germain prime.

Together with 666533323, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (666533323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333266660 + 333266661.

It is an arithmetic number, because the mean of its divisors is an integer number (333266661).

Almost surely, 2^666533321 is an apocalyptic number.

It is an amenable number.

666533321 is a deficient number, since it is larger than the sum of its proper divisors (1).

666533321 is an equidigital number, since it uses as much as digits as its factorization.

666533321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58320, while the sum is 35.

The square root of 666533321 is about 25817.3066178484. The cubic root of 666533321 is about 873.5222167678.

Adding to 666533321 its reverse (123335666), we get a palindrome (789868987).

The spelling of 666533321 in words is "six hundred sixty-six million, five hundred thirty-three thousand, three hundred twenty-one".