728720 has 20 divisors (see below), whose sum is σ = 1694460. Its totient is φ = 291456.

The previous prime is 728713. The next prime is 728723. The reversal of 728720 is 27827.

It can be written as a sum of positive squares in 2 ways, for example, as 163216 + 565504 = 404^2 + 752^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 728720.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 728720.

It is not an unprimeable number, because it can be changed into a prime (728723) by changing a digit.

728720 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4475 + ... + 4634.

It is an arithmetic number, because the mean of its divisors is an integer number (84723).

2⁷²⁸⁷²⁰ is an apocalyptic number.

It is an amenable number.

728720 is an abundant number, since it is smaller than the sum of its proper divisors (965740).

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

728720 is a wasteful number, since it uses less digits than its factorization.

728720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9122 (or 9116 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 26.

The square root of 728720 is about 853.6509825450. The cubic root of 728720 is about 89.9884758907.

The spelling of 728720 in words is "seven hundred twenty-eight thousand, seven hundred twenty".