720068161 has 4 divisors (see below), whose sum is σ = 720130132. Its totient is φ = 720006192.

The previous prime is 720068147. The next prime is 720068171. The reversal of 720068161 is 161860027.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 161860027 = 7 ⋅23122861.

It can be written as a sum of positive squares in 2 ways, for example, as 91011600 + 629056561 = 9540^2 + 25081^2 .

It is a 3-Lehmer number, since φ(720068161) divides (720068161-1)³.

It is a cyclic number.

It is not a de Polignac number, because 720068161 - 2⁷ = 720068033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (720068171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7746 + ... + 38731.

It is an arithmetic number, because the mean of its divisors is an integer number (180032533).

Almost surely, 2^720068161 is an apocalyptic number.

720068161 is the 15493-rd octagonal number.

It is an amenable number.

720068161 is a deficient number, since it is larger than the sum of its proper divisors (61971).

720068161 is a wasteful number, since it uses less digits than its factorization.

720068161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61970.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 720068161 is about 26834.0858051844. The cubic root of 720068161 is about 896.3092314772.

The spelling of 720068161 in words is "seven hundred twenty million, sixty-eight thousand, one hundred sixty-one".