665729864 has 8 divisors (see below), whose sum is σ = 1248243510. Its totient is φ = 332864928.

The previous prime is 665729861. The next prime is 665729921. The reversal of 665729864 is 468927566.

It can be written as a sum of positive squares in only one way, i.e., 371332900 + 294396964 = 19270^2 + 17158^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (665729861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41608109 + ... + 41608124.

Almost surely, 2^665729864 is an apocalyptic number.

It is an amenable number.

665729864 is a deficient number, since it is larger than the sum of its proper divisors (582513646).

665729864 is a wasteful number, since it uses less digits than its factorization.

665729864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83216239 (or 83216235 counting only the distinct ones).

The product of its digits is 4354560, while the sum is 53.

The square root of 665729864 is about 25801.7414916125. The cubic root of 665729864 is about 873.1710866687.

The spelling of 665729864 in words is "six hundred sixty-five million, seven hundred twenty-nine thousand, eight hundred sixty-four".