640924728 has 16 divisors (see below), whose sum is σ = 1602311880. Its totient is φ = 213641568.

The previous prime is 640924727. The next prime is 640924787. The reversal of 640924728 is 827429046.

640924728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (42) 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 640924728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640924727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13352575 + ... + 13352622.

Almost surely, 2^640924728 is an apocalyptic number.

It is an amenable number.

640924728 is an abundant number, since it is smaller than the sum of its proper divisors (961387152).

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

640924728 is a wasteful number, since it uses less digits than its factorization.

640924728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26705206 (or 26705202 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 42.

The square root of 640924728 is about 25316.4912260763. The cubic root of 640924728 is about 862.1887317040.

The spelling of 640924728 in words is "six hundred forty million, nine hundred twenty-four thousand, seven hundred twenty-eight".