728766721 has 2 divisors, whose sum is σ = 728766722. Its totient is φ = 728766720.

The previous prime is 728766683. The next prime is 728766737. The reversal of 728766721 is 127667827.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 541213696 + 187553025 = 23264^2 + 13695^2 .

It is a cyclic number.

It is not a de Polignac number, because 728766721 - 2¹³ = 728758529 is a prime.

It is a super-2 number, since 2×728766721² = 1062201867274183682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (728766751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364383360 + 364383361.

It is an arithmetic number, because the mean of its divisors is an integer number (364383361).

Almost surely, 2^728766721 is an apocalyptic number.

It is an amenable number.

728766721 is a deficient number, since it is larger than the sum of its proper divisors (1).

728766721 is an equidigital number, since it uses as much as digits as its factorization.

728766721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 395136, while the sum is 46.

The square root of 728766721 is about 26995.6796728662. The cubic root of 728766721 is about 899.9039901698.

It can be divided in two parts, 72876 and 6721, that added together give a palindrome (79597).

The spelling of 728766721 in words is "seven hundred twenty-eight million, seven hundred sixty-six thousand, seven hundred twenty-one".