161644855165369 has 27 divisors (see below), whose sum is σ = 169463136621037. Its totient is φ = 154174600923200.

The previous prime is 161644855165363. The next prime is 161644855165379. The reversal of 161644855165369 is 963561558446161.

The square root of 161644855165369 is 12713963.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 561544905769 + 161083310259600 = 749363^2 + 12691860^2 .

It is not a de Polignac number, because 161644855165369 - 2⁹ = 161644855164857 is a prime.

It is a super-2 number, since 2×161644855165369² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161644855165298 and 161644855165307.

It is not an unprimeable number, because it can be changed into a prime (161644855165363) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 152351418099 + ... + 152351419159.

Almost surely, 2^{161644855165369} is an apocalyptic number.

161644855165369 is the 12713963-rd square number.

161644855165369 is the 6356982-nd centered octagonal number.

It is an amenable number.

161644855165369 is a deficient number, since it is larger than the sum of its proper divisors (7818281455668).

161644855165369 is an frugal number, since it uses more digits than its factorization.

161644855165369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3210 (or 1605 counting only the distinct ones).

The product of its digits is 559872000, while the sum is 70.

The spelling of 161644855165369 in words is "one hundred sixty-one trillion, six hundred forty-four billion, eight hundred fifty-five million, one hundred sixty-five thousand, three hundred sixty-nine".