664637717 has 4 divisors (see below), whose sum is σ = 664690560. Its totient is φ = 664584876.

The previous prime is 664637711. The next prime is 664637759. The reversal of 664637717 is 717736466.

664637717 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 Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 717736466 = 2 ⋅358868233.

It is a cyclic number.

It is not a de Polignac number, because 664637717 - 2⁶ = 664637653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664637711) 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, 4538 + ... + 36740.

It is an arithmetic number, because the mean of its divisors is an integer number (166172640).

Almost surely, 2^664637717 is an apocalyptic number.

It is an amenable number.

664637717 is a deficient number, since it is larger than the sum of its proper divisors (52843).

664637717 is a wasteful number, since it uses less digits than its factorization.

664637717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52842.

The product of its digits is 889056, while the sum is 47.

The square root of 664637717 is about 25780.5685934193. The cubic root of 664637717 is about 872.6933387634.

The spelling of 664637717 in words is "six hundred sixty-four million, six hundred thirty-seven thousand, seven hundred seventeen".