921728 has 32 divisors (see below), whose sum is σ = 1938000. Its totient is φ = 435456.

The previous prime is 921703. The next prime is 921733. The reversal of 921728 is 827129.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (32).

It is a self number, because there is not a number n which added to its sum of digits gives 921728.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 921728.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2243 + ... + 2621.

2⁹²¹⁷²⁸ 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 921728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (969000).

921728 is an abundant number, since it is smaller than the sum of its proper divisors (1016272).

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

921728 is a wasteful number, since it uses less digits than its factorization.

921728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412 (or 400 counting only the distinct ones).

The product of its digits is 2016, while the sum is 29.

The square root of 921728 is about 960.0666643520. The cubic root of 921728 is about 97.3197370554.

The spelling of 921728 in words is "nine hundred twenty-one thousand, seven hundred twenty-eight".