728320121 has 2 divisors, whose sum is σ = 728320122. Its totient is φ = 728320120.

The previous prime is 728320097. The next prime is 728320129. The reversal of 728320121 is 121023827.

728320121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 547794025 + 180526096 = 23405^2 + 13436^2 .

It is an emirp because it is prime and its reverse (121023827) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-728320121 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (728320129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364160060 + 364160061.

It is an arithmetic number, because the mean of its divisors is an integer number (364160061).

Almost surely, 2^728320121 is an apocalyptic number.

It is an amenable number.

728320121 is a deficient number, since it is larger than the sum of its proper divisors (1).

728320121 is an equidigital number, since it uses as much as digits as its factorization.

728320121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 728320121 is about 26987.4067112792. The cubic root of 728320121 is about 899.7201273804.

Adding to 728320121 its reverse (121023827), we get a palindrome (849343948).

The spelling of 728320121 in words is "seven hundred twenty-eight million, three hundred twenty thousand, one hundred twenty-one".