666604617655 has 16 divisors (see below), whose sum is σ = 805422758400. Its totient is φ = 529630502400.

The previous prime is 666604617607. The next prime is 666604617673. The reversal of 666604617655 is 556716406666.

It is not a de Polignac number, because 666604617655 - 2⁷ = 666604617527 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 666604617655.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 266775 + ... + 1185064.

It is an arithmetic number, because the mean of its divisors is an integer number (50338922400).

Almost surely, 2^666604617655 is an apocalyptic number.

666604617655 is a deficient number, since it is larger than the sum of its proper divisors (138818140745).

666604617655 is a wasteful number, since it uses less digits than its factorization.

666604617655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1452474.

The product of its (nonzero) digits is 32659200, while the sum is 58.

The spelling of 666604617655 in words is "six hundred sixty-six billion, six hundred four million, six hundred seventeen thousand, six hundred fifty-five".