66318391 has 2 divisors, whose sum is σ = 66318392. Its totient is φ = 66318390.

The previous prime is 66318359. The next prime is 66318397. The reversal of 66318391 is 19381366.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66318391 - 2⁵ = 66318359 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66318391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66318397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33159195 + 33159196.

It is an arithmetic number, because the mean of its divisors is an integer number (33159196).

Almost surely, 2^66318391 is an apocalyptic number.

66318391 is a deficient number, since it is larger than the sum of its proper divisors (1).

66318391 is an equidigital number, since it uses as much as digits as its factorization.

66318391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 37.

The square root of 66318391 is about 8143.6104400935. The cubic root of 66318391 is about 404.7728055615.

The spelling of 66318391 in words is "sixty-six million, three hundred eighteen thousand, three hundred ninety-one".