728005 has 4 divisors (see below), whose sum is σ = 873612. Its totient is φ = 582400.

The previous prime is 728003. The next prime is 728017. The reversal of 728005 is 500827.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 500827 = 181 ⋅2767.

It can be written as a sum of positive squares in 2 ways, for example, as 471969 + 256036 = 687^2 + 506^2 .

It is not a de Polignac number, because 728005 - 2¹ = 728003 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728003) 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, 72796 + ... + 72805.

It is an arithmetic number, because the mean of its divisors is an integer number (218403).

2⁷²⁸⁰⁰⁵ is an apocalyptic number.

It is an amenable number.

728005 is a deficient number, since it is larger than the sum of its proper divisors (145607).

728005 is a wasteful number, since it uses less digits than its factorization.

728005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145606.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 728005 is about 853.2320903482. The cubic root of 728005 is about 89.9590348547.

The spelling of 728005 in words is "seven hundred twenty-eight thousand, five".