664723665 has 40 divisors (see below), whose sum is σ = 1194842088. Its totient is φ = 353548800.

The previous prime is 664723651. The next prime is 664723687. The reversal of 664723665 is 566327466.

664723665 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 225360144 + 439363521 = 15012^2 + 20961^2 .

It is not a de Polignac number, because 664723665 - 2⁶ = 664723601 is a prime.

It is a super-2 number, since 2×664723665² = 883715101622064450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 664723665.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 160359 + ... + 164451.

Almost surely, 2^664723665 is an apocalyptic number.

It is an amenable number.

664723665 is a deficient number, since it is larger than the sum of its proper divisors (530118423).

664723665 is a wasteful number, since it uses less digits than its factorization.

664723665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4511 (or 4502 counting only the distinct ones).

The product of its digits is 1088640, while the sum is 45.

The square root of 664723665 is about 25782.2354538934. The cubic root of 664723665 is about 872.7309547519.

The spelling of 664723665 in words is "six hundred sixty-four million, seven hundred twenty-three thousand, six hundred sixty-five".