666505655 has 32 divisors (see below), whose sum is σ = 894965760. Its totient is φ = 473541120.

The previous prime is 666505639. The next prime is 666505657. The reversal of 666505655 is 556505666.

It is not a de Polignac number, because 666505655 - 2⁴ = 666505639 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666505657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 501602 + ... + 502928.

It is an arithmetic number, because the mean of its divisors is an integer number (27967680).

Almost surely, 2^666505655 is an apocalyptic number.

666505655 is a deficient number, since it is larger than the sum of its proper divisors (228460105).

666505655 is a wasteful number, since it uses less digits than its factorization.

666505655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1679.

The product of its (nonzero) digits is 810000, while the sum is 44.

The square root of 666505655 is about 25816.7708089141. The cubic root of 666505655 is about 873.5101307504.

The spelling of 666505655 in words is "six hundred sixty-six million, five hundred five thousand, six hundred fifty-five".