728323989561 has 27 divisors (see below), whose sum is σ = 1223812600101. Its totient is φ = 416174895864.

The previous prime is 728323989527. The next prime is 728323989577. The reversal of 728323989561 is 165989323827.

The square root of 728323989561 is 853419.

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

728323989561 is a `hidden beast` number, since 7 + 2 + 8 + 32 + 39 + 8 + 9 + 561 = 666.

It is not a de Polignac number, because 728323989561 - 2⁷ = 728323989433 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (728323989511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 17901480 + ... + 17942118.

Almost surely, 2^728323989561 is an apocalyptic number.

728323989561 is the 853419-th square number.

728323989561 is the 426710-th centered octagonal number.

It is an amenable number.

728323989561 is a deficient number, since it is larger than the sum of its proper divisors (495488610540).

728323989561 is an frugal number, since it uses more digits than its factorization.

728323989561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81298 (or 40649 counting only the distinct ones).

The product of its digits is 39191040, while the sum is 63.

The spelling of 728323989561 in words is "seven hundred twenty-eight billion, three hundred twenty-three million, nine hundred eighty-nine thousand, five hundred sixty-one".