161751822712561 has 9 divisors (see below), whose sum is σ = 161971189925889. Its totient is φ = 161532752251536.

The previous prime is 161751822712541. The next prime is 161751822712577. The reversal of 161751822712561 is 165217228157161.

It is a happy number.

The square root of 161751822712561 is 12718169.

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 114163570161 + 161637659142400 = 337881^2 + 12713680^2 .

It is not a de Polignac number, because 161751822712561 - 2¹⁵ = 161751822679793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161751822712541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 9831136411 + ... + 9831152863.

Almost surely, 2^{161751822712561} is an apocalyptic number.

161751822712561 is the 12718169-th square number.

161751822712561 is the 6359085-th centered octagonal number.

It is an amenable number.

161751822712561 is a deficient number, since it is larger than the sum of its proper divisors (219367213328).

161751822712561 is an frugal number, since it uses more digits than its factorization.

161751822712561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34452 (or 17226 counting only the distinct ones).

The product of its digits is 2822400, while the sum is 55.

The spelling of 161751822712561 in words is "one hundred sixty-one trillion, seven hundred fifty-one billion, eight hundred twenty-two million, seven hundred twelve thousand, five hundred sixty-one".