666556765 has 16 divisors (see below), whose sum is σ = 962248320. Its totient is φ = 433010880.

The previous prime is 666556729. The next prime is 666556783. The reversal of 666556765 is 567655666.

It is not a de Polignac number, because 666556765 - 2²¹ = 664459613 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 500506 + ... + 501835.

It is an arithmetic number, because the mean of its divisors is an integer number (60140520).

Almost surely, 2^666556765 is an apocalyptic number.

It is an amenable number.

666556765 is a deficient number, since it is larger than the sum of its proper divisors (295691555).

666556765 is a wasteful number, since it uses less digits than its factorization.

666556765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1002372.

The product of its digits is 6804000, while the sum is 52.

The square root of 666556765 is about 25817.7606503740. The cubic root of 666556765 is about 873.5324581237.

The spelling of 666556765 in words is "six hundred sixty-six million, five hundred fifty-six thousand, seven hundred sixty-five".