72720161 has 2 divisors, whose sum is σ = 72720162. Its totient is φ = 72720160.

The previous prime is 72720143. The next prime is 72720199. The reversal of 72720161 is 16102727.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 71081761 + 1638400 = 8431^2 + 1280^2 .

It is a cyclic number.

It is not a de Polignac number, because 72720161 - 2⁶ = 72720097 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 72720161.

It is not a weakly prime, because it can be changed into another prime (72720121) 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 as a sum of consecutive naturals, namely, 36360080 + 36360081.

It is an arithmetic number, because the mean of its divisors is an integer number (36360081).

Almost surely, 2^72720161 is an apocalyptic number.

It is an amenable number.

72720161 is a deficient number, since it is larger than the sum of its proper divisors (1).

72720161 is an equidigital number, since it uses as much as digits as its factorization.

72720161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 26.

The square root of 72720161 is about 8527.6116820596. The cubic root of 72720161 is about 417.3991982969.

Adding to 72720161 its reverse (16102727), we get a palindrome (88822888).

The spelling of 72720161 in words is "seventy-two million, seven hundred twenty thousand, one hundred sixty-one".