664868791 has 2 divisors, whose sum is σ = 664868792. Its totient is φ = 664868790.

The previous prime is 664868747. The next prime is 664868801. The reversal of 664868791 is 197868466.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 664868791 - 2¹¹ = 664866743 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664868731) 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, 332434395 + 332434396.

It is an arithmetic number, because the mean of its divisors is an integer number (332434396).

Almost surely, 2^664868791 is an apocalyptic number.

664868791 is a deficient number, since it is larger than the sum of its proper divisors (1).

664868791 is an equidigital number, since it uses as much as digits as its factorization.

664868791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3483648, while the sum is 55.

The square root of 664868791 is about 25785.0497575630. The cubic root of 664868791 is about 872.7944632156.

The spelling of 664868791 in words is "six hundred sixty-four million, eight hundred sixty-eight thousand, seven hundred ninety-one".