72566123161 has 27 divisors (see below), whose sum is σ = 87490773279. Its totient is φ = 60009466608.

The previous prime is 72566123117. The next prime is 72566123213. The reversal of 72566123161 is 16132166527.

The square root of 72566123161 is 269381.

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

It can be written as a sum of positive squares in only one way, i.e., 38051914761 + 34514208400 = 195069^2 + 185780^2 .

It is not a de Polignac number, because 72566123161 - 2⁹ = 72566122649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (72566123561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 54683680 + ... + 54685006.

Almost surely, 2^72566123161 is an apocalyptic number.

72566123161 is the 269381-st square number.

72566123161 is the 134691-st centered octagonal number.

It is an amenable number.

72566123161 is a deficient number, since it is larger than the sum of its proper divisors (14924650118).

72566123161 is an frugal number, since it uses more digits than its factorization.

72566123161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2726 (or 1363 counting only the distinct ones).

The product of its digits is 90720, while the sum is 40.

Adding to 72566123161 its reverse (16132166527), we get a palindrome (88698289688).

The spelling of 72566123161 in words is "seventy-two billion, five hundred sixty-six million, one hundred twenty-three thousand, one hundred sixty-one".