166851868644 has 18 divisors (see below), whose sum is σ = 421764445830. Its totient is φ = 55617289536.

The previous prime is 166851868639. The next prime is 166851868657. The reversal of 166851868644 is 446868158661.

166851868644 is a `hidden beast` number, since 16 + 6 + 8 + 518 + 68 + 6 + 44 = 666.

It can be written as a sum of positive squares in only one way, i.e., 99206100900 + 67645767744 = 314970^2 + 260088^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2317387029 + ... + 2317387100.

Almost surely, 2^166851868644 is an apocalyptic number.

It is an amenable number.

166851868644 is an abundant number, since it is smaller than the sum of its proper divisors (254912577186).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

166851868644 is a wasteful number, since it uses less digits than its factorization.

166851868644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4634774139 (or 4634774134 counting only the distinct ones).

The product of its digits is 53084160, while the sum is 63.

The spelling of 166851868644 in words is "one hundred sixty-six billion, eight hundred fifty-one million, eight hundred sixty-eight thousand, six hundred forty-four".