728305 has 4 divisors (see below), whose sum is σ = 873972. Its totient is φ = 582640.

The previous prime is 728303. The next prime is 728317. The reversal of 728305 is 503827.

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 222784 + 505521 = 472^2 + 711^2 .

It is not a de Polignac number, because 728305 - 2¹ = 728303 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 728305.

It is not an unprimeable number, because it can be changed into a prime (728303) 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 in 3 ways as a sum of consecutive naturals, for example, 72826 + ... + 72835.

It is an arithmetic number, because the mean of its divisors is an integer number (218493).

2⁷²⁸³⁰⁵ is an apocalyptic number.

It is an amenable number.

728305 is a deficient number, since it is larger than the sum of its proper divisors (145667).

728305 is a wasteful number, since it uses less digits than its factorization.

728305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145666.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 728305 is about 853.4078743485. The cubic root of 728305 is about 89.9713900832.

It can be divided in two parts, 7 and 28305, that multiplied together give a triangular number (198135 = T₆₂₉).

The spelling of 728305 in words is "seven hundred twenty-eight thousand, three hundred five".