640931000 has 64 divisors (see below), whose sum is σ = 1506098880. Its totient is φ = 255292800.

The previous prime is 640930931. The next prime is 640931003. The reversal of 640931000 is 139046.

640931000 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×640931000³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640931003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 261782 + ... + 264218.

It is an arithmetic number, because the mean of its divisors is an integer number (23532795).

Almost surely, 2^640931000 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 640931000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (753049440).

640931000 is an abundant number, since it is smaller than the sum of its proper divisors (865167880).

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

640931000 is a wasteful number, since it uses less digits than its factorization.

640931000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2721 (or 2707 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 640931000 is about 25316.6150975994. The cubic root of 640931000 is about 862.1915441144.

The spelling of 640931000 in words is "six hundred forty million, nine hundred thirty-one thousand".