728605 has 4 divisors (see below), whose sum is σ = 874332. Its totient is φ = 582880.

The previous prime is 728579. The next prime is 728627. The reversal of 728605 is 506827.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 506827 = 367 ⋅1381.

It can be written as a sum of positive squares in 2 ways, for example, as 375769 + 352836 = 613^2 + 594^2 .

It is not a de Polignac number, because 728605 - 2⁵ = 728573 is a prime.

It is a Duffinian number.

728605 is a lucky number.

It is a congruent number.

It is an unprimeable number.

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, 72856 + ... + 72865.

It is an arithmetic number, because the mean of its divisors is an integer number (218583).

2⁷²⁸⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

728605 is a deficient number, since it is larger than the sum of its proper divisors (145727).

728605 is a wasteful number, since it uses less digits than its factorization.

728605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145726.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 728605 is about 853.5836221484. The cubic root of 728605 is about 89.9837419192.

The spelling of 728605 in words is "seven hundred twenty-eight thousand, six hundred five".