161605661656864 has 48 divisors (see below), whose sum is σ = 324435912813432. Its totient is φ = 79211795273728.

The previous prime is 161605661656853. The next prime is 161605661656927. The reversal of 161605661656864 is 468656166506161.

It can be written as a sum of positive squares in 4 ways, for example, as 118198383560464 + 43407278096400 = 10871908^2 + 6588420^2 .

It is a super-2 number, since 2×161605661656864² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161605661656864.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 37912279 + ... + 41958934.

Almost surely, 2^{161605661656864} is an apocalyptic number.

It is an amenable number.

161605661656864 is an abundant number, since it is smaller than the sum of its proper divisors (162830251156568).

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

161605661656864 is a wasteful number, since it uses less digits than its factorization.

161605661656864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79872469 (or 79872461 counting only the distinct ones).

The product of its (nonzero) digits is 223948800, while the sum is 67.

The spelling of 161605661656864 in words is "one hundred sixty-one trillion, six hundred five billion, six hundred sixty-one million, six hundred fifty-six thousand, eight hundred sixty-four".