728209 has 2 divisors, whose sum is σ = 728210. Its totient is φ = 728208.

The previous prime is 728207. The next prime is 728261. The reversal of 728209 is 902827.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 88209 = 800^2 + 297^2 .

It is an emirp because it is prime and its reverse (902827) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 728209 - 2¹ = 728207 is a prime.

Together with 728207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (728207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364104 + 364105.

It is an arithmetic number, because the mean of its divisors is an integer number (364105).

2⁷²⁸²⁰⁹ is an apocalyptic number.

It is an amenable number.

728209 is a deficient number, since it is larger than the sum of its proper divisors (1).

728209 is an equidigital number, since it uses as much as digits as its factorization.

728209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 728209 is about 853.3516274081. The cubic root of 728209 is about 89.9674367793.

It can be divided in two parts, 72 and 8209, that added together give a square (8281 = 91²).

The spelling of 728209 in words is "seven hundred twenty-eight thousand, two hundred nine".