161776765 has 16 divisors (see below), whose sum is σ = 199818288. Its totient is φ = 125646336.

The previous prime is 161776763. The next prime is 161776781. The reversal of 161776765 is 567677161.

It can be written as a sum of positive squares in 8 ways, for example, as 34786404 + 126990361 = 5898^2 + 11269^2 .

It is a cyclic number.

It is not a de Polignac number, because 161776765 - 2¹ = 161776763 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161776763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 135009 + ... + 136201.

It is an arithmetic number, because the mean of its divisors is an integer number (12488643).

Almost surely, 2^161776765 is an apocalyptic number.

It is an amenable number.

161776765 is a deficient number, since it is larger than the sum of its proper divisors (38041523).

161776765 is a wasteful number, since it uses less digits than its factorization.

161776765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1968.

The product of its digits is 370440, while the sum is 46.

The square root of 161776765 is about 12719.1495391791. The cubic root of 161776765 is about 544.8856646498.

The spelling of 161776765 in words is "one hundred sixty-one million, seven hundred seventy-six thousand, seven hundred sixty-five".