161853802821 has 6 divisors (see below), whose sum is σ = 233788826310. Its totient is φ = 107902535208.

The previous prime is 161853802763. The next prime is 161853802843. The reversal of 161853802821 is 128208358161.

161853802821 is a `hidden beast` number, since 1 + 618 + 5 + 3 + 8 + 0 + 2 + 8 + 21 = 666.

161853802821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 94611608100 + 67242194721 = 307590^2 + 259311^2 .

It is not a de Polignac number, because 161853802821 - 2⁹ = 161853802309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161853807821) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 8991877926 + ... + 8991877943.

It is an arithmetic number, because the mean of its divisors is an integer number (38964804385).

Almost surely, 2^161853802821 is an apocalyptic number.

It is an amenable number.

161853802821 is a deficient number, since it is larger than the sum of its proper divisors (71935023489).

161853802821 is a wasteful number, since it uses less digits than its factorization.

161853802821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17983755875 (or 17983755872 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 45.

The spelling of 161853802821 in words is "one hundred sixty-one billion, eight hundred fifty-three million, eight hundred two thousand, eight hundred twenty-one".