321728 has 28 divisors (see below), whose sum is σ = 697992. Its totient is φ = 145920.

The previous prime is 321721. The next prime is 321733. The reversal of 321728 is 827123.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 321728.

It is not an unprimeable number, because it can be changed into a prime (321721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 476 + ... + 932.

2³²¹⁷²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 321728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (348996).

321728 is an abundant number, since it is smaller than the sum of its proper divisors (376264).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

321728 is a wasteful number, since it uses less digits than its factorization.

321728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 480 (or 470 counting only the distinct ones).

The product of its digits is 672, while the sum is 23.

The square root of 321728 is about 567.2107192217. The cubic root of 321728 is about 68.5219351848.

The spelling of 321728 in words is "three hundred twenty-one thousand, seven hundred twenty-eight".