728221 has 12 divisors (see below), whose sum is σ = 819840. Its totient is φ = 645840.

The previous prime is 728209. The next prime is 728261. The reversal of 728221 is 122827.

It is a de Polignac number, because none of the positive numbers 2^k-728221 is a prime.

It is a Duffinian number.

728221 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 728192 and 728201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728261) 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 11 ways as a sum of consecutive naturals, for example, 5170 + ... + 5308.

It is an arithmetic number, because the mean of its divisors is an integer number (68320).

2⁷²⁸²²¹ is an apocalyptic number.

It is an amenable number.

728221 is a deficient number, since it is larger than the sum of its proper divisors (91619).

728221 is a wasteful number, since it uses less digits than its factorization.

728221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 183 counting only the distinct ones).

The product of its digits is 448, while the sum is 22.

The square root of 728221 is about 853.3586584784. The cubic root of 728221 is about 89.9679309613.

It can be divided in two parts, 728 and 221, that added together give a palindrome (949).

The spelling of 728221 in words is "seven hundred twenty-eight thousand, two hundred twenty-one".