645307728 has 40 divisors (see below), whose sum is σ = 1795280928. Its totient is φ = 198556032.

The previous prime is 645307723. The next prime is 645307771. The reversal of 645307728 is 827703546.

645307728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 645307728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645307723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 516450 + ... + 517697.

Almost surely, 2^645307728 is an apocalyptic number.

It is an amenable number.

645307728 is an abundant number, since it is smaller than the sum of its proper divisors (1149973200).

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

645307728 is a wasteful number, since it uses less digits than its factorization.

645307728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1034171 (or 1034165 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 42.

The square root of 645307728 is about 25402.9078650457. The cubic root of 645307728 is about 864.1496440049.

The spelling of 645307728 in words is "six hundred forty-five million, three hundred seven thousand, seven hundred twenty-eight".