728640 has 168 divisors, whose sum is σ = 2852928. Its totient is φ = 168960.

The previous prime is 728639. The next prime is 728647. The reversal of 728640 is 46827.

728640 = 87² + 88² + ... + 141².

It is not an unprimeable number, because it can be changed into a prime (728647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31669 + ... + 31691.

2⁷²⁸⁶⁴⁰ 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 728640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1426464).

728640 is an abundant number, since it is smaller than the sum of its proper divisors (2124288).

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

728640 is a wasteful number, since it uses less digits than its factorization.

728640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57 (or 44 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 728640 is about 853.6041237014. The cubic root of 728640 is about 89.9851827459.

The spelling of 728640 in words is "seven hundred twenty-eight thousand, six hundred forty".