66664321 has 2 divisors, whose sum is σ = 66664322. Its totient is φ = 66664320.

The previous prime is 66664307. The next prime is 66664349. The reversal of 66664321 is 12346666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62583921 + 4080400 = 7911^2 + 2020^2 .

It is a cyclic number.

It is not a de Polignac number, because 66664321 - 2⁷ = 66664193 is a prime.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (66664391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33332160 + 33332161.

It is an arithmetic number, because the mean of its divisors is an integer number (33332161).

Almost surely, 2^66664321 is an apocalyptic number.

It is an amenable number.

66664321 is a deficient number, since it is larger than the sum of its proper divisors (1).

66664321 is an equidigital number, since it uses as much as digits as its factorization.

66664321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 34.

The square root of 66664321 is about 8164.8221658527. The cubic root of 66664321 is about 405.4753773763.

The spelling of 66664321 in words is "sixty-six million, six hundred sixty-four thousand, three hundred twenty-one".