728851561 has 4 divisors (see below), whose sum is σ = 729753300. Its totient is φ = 727949824.

The previous prime is 728851559. The next prime is 728851583. The reversal of 728851561 is 165158827.

728851561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 359481600 + 369369961 = 18960^2 + 19219^2 .

It is a cyclic number.

It is not a de Polignac number, because 728851561 - 2¹ = 728851559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (728851511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 449656 + ... + 451273.

It is an arithmetic number, because the mean of its divisors is an integer number (182438325).

Almost surely, 2^728851561 is an apocalyptic number.

It is an amenable number.

728851561 is a deficient number, since it is larger than the sum of its proper divisors (901739).

728851561 is an equidigital number, since it uses as much as digits as its factorization.

728851561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 901738.

The product of its digits is 134400, while the sum is 43.

The square root of 728851561 is about 26997.2509896841. The cubic root of 728851561 is about 899.9389098452.

The spelling of 728851561 in words is "seven hundred twenty-eight million, eight hundred fifty-one thousand, five hundred sixty-one".