155668866561 has 12 divisors (see below), whose sum is σ = 242151570388. Its totient is φ = 95796225504.

The previous prime is 155668866511. The next prime is 155668866599. The reversal of 155668866561 is 165668866551.

155668866561 is a `hidden beast` number, since 1 + 5 + 5 + 6 + 6 + 8 + 8 + 66 + 561 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 70897050225 + 84771816336 = 266265^2 + 291156^2 .

It is not a de Polignac number, because 155668866561 - 2⁹ = 155668866049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (155668866511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 665251450 + ... + 665251683.

Almost surely, 2^155668866561 is an apocalyptic number.

It is an amenable number.

155668866561 is a deficient number, since it is larger than the sum of its proper divisors (86482703827).

155668866561 is a wasteful number, since it uses less digits than its factorization.

155668866561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1330503152 (or 1330503149 counting only the distinct ones).

The product of its digits is 62208000, while the sum is 63.

The spelling of 155668866561 in words is "one hundred fifty-five billion, six hundred sixty-eight million, eight hundred sixty-six thousand, five hundred sixty-one".