640925628 has 24 divisors (see below), whose sum is σ = 1709135232. Its totient is φ = 183121584.

The previous prime is 640925627. The next prime is 640925641. The reversal of 640925628 is 826529046.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 640925628.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640925627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3814950 + ... + 3815117.

It is an arithmetic number, because the mean of its divisors is an integer number (71213968).

Almost surely, 2^640925628 is an apocalyptic number.

It is an amenable number.

640925628 is an abundant number, since it is smaller than the sum of its proper divisors (1068209604).

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

640925628 is a wasteful number, since it uses less digits than its factorization.

640925628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7630081 (or 7630079 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The square root of 640925628 is about 25316.5090010451. The cubic root of 640925628 is about 862.1891352717.

The spelling of 640925628 in words is "six hundred forty million, nine hundred twenty-five thousand, six hundred twenty-eight".