161605566661656 has 128 divisors (see below), whose sum is σ = 435672285189120. Its totient is φ = 49658505667584.

The previous prime is 161605566661631. The next prime is 161605566661661. The reversal of 161605566661656 is 656166665506161.

It is a super-2 number, since 2×161605566661656² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 706472356 + ... + 706701068.

It is an arithmetic number, because the mean of its divisors is an integer number (3403689728040).

Almost surely, 2^{161605566661656} is an apocalyptic number.

It is an amenable number.

161605566661656 is an abundant number, since it is smaller than the sum of its proper divisors (274066718527464).

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

161605566661656 is a wasteful number, since it uses less digits than its factorization.

161605566661656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231745 (or 231741 counting only the distinct ones).

The product of its (nonzero) digits is 209952000, while the sum is 66.

The spelling of 161605566661656 in words is "one hundred sixty-one trillion, six hundred five billion, five hundred sixty-six million, six hundred sixty-one thousand, six hundred fifty-six".