664779686 has 16 divisors (see below), whose sum is σ = 1032238080. Its totient is φ = 320760840.

The previous prime is 664779667. The next prime is 664779691. The reversal of 664779686 is 686977466.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7325 + ... + 37191.

It is an arithmetic number, because the mean of its divisors is an integer number (64514880).

Almost surely, 2^664779686 is an apocalyptic number.

664779686 is a deficient number, since it is larger than the sum of its proper divisors (367458394).

664779686 is a wasteful number, since it uses less digits than its factorization.

664779686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30259.

The product of its digits is 18289152, while the sum is 59.

The square root of 664779686 is about 25783.3218573558. The cubic root of 664779686 is about 872.7554711487.

The spelling of 664779686 in words is "six hundred sixty-four million, seven hundred seventy-nine thousand, six hundred eighty-six".