664705091 has 4 divisors (see below), whose sum is σ = 664759872. Its totient is φ = 664650312.

The previous prime is 664705039. The next prime is 664705099. The reversal of 664705091 is 190507466.

664705091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664705091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664705099) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 176 + ... + 36461.

It is an arithmetic number, because the mean of its divisors is an integer number (166189968).

Almost surely, 2^664705091 is an apocalyptic number.

664705091 is a deficient number, since it is larger than the sum of its proper divisors (54781).

664705091 is a wasteful number, since it uses less digits than its factorization.

664705091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54780.

The product of its (nonzero) digits is 45360, while the sum is 38.

The square root of 664705091 is about 25781.8752421153. The cubic root of 664705091 is about 872.7228259325.

The spelling of 664705091 in words is "six hundred sixty-four million, seven hundred five thousand, ninety-one".