728637561 has 12 divisors (see below), whose sum is σ = 1114387092. Its totient is φ = 457184256.

The previous prime is 728637541. The next prime is 728637563. The reversal of 728637561 is 165736827.

728637561 is a `hidden beast` number, since 7 + 2 + 8 + 637 + 5 + 6 + 1 = 666.

728637561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 626000400 + 102637161 = 25020^2 + 10131^2 .

It is not a de Polignac number, because 728637561 - 2¹⁰ = 728636537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (728637563) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2381016 + ... + 2381321.

It is an arithmetic number, because the mean of its divisors is an integer number (92865591).

Almost surely, 2^728637561 is an apocalyptic number.

It is an amenable number.

728637561 is a deficient number, since it is larger than the sum of its proper divisors (385749531).

728637561 is a wasteful number, since it uses less digits than its factorization.

728637561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4762360 (or 4762357 counting only the distinct ones).

The product of its digits is 423360, while the sum is 45.

The square root of 728637561 is about 26993.2873322239. The cubic root of 728637561 is about 899.8508234232.

The spelling of 728637561 in words is "seven hundred twenty-eight million, six hundred thirty-seven thousand, five hundred sixty-one".