66665213 has 2 divisors, whose sum is σ = 66665214. Its totient is φ = 66665212.

The previous prime is 66665197. The next prime is 66665227. The reversal of 66665213 is 31256666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49042009 + 17623204 = 7003^2 + 4198^2 .

It is a cyclic number.

It is not a de Polignac number, because 66665213 - 2⁴ = 66665197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66665233) 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, 33332606 + 33332607.

It is an arithmetic number, because the mean of its divisors is an integer number (33332607).

Almost surely, 2^66665213 is an apocalyptic number.

It is an amenable number.

66665213 is a deficient number, since it is larger than the sum of its proper divisors (1).

66665213 is an equidigital number, since it uses as much as digits as its factorization.

66665213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 35.

The square root of 66665213 is about 8164.8767902523. The cubic root of 66665213 is about 405.4771858520.

The spelling of 66665213 in words is "sixty-six million, six hundred sixty-five thousand, two hundred thirteen".