640968 has 32 divisors (see below), whose sum is σ = 1697760. Its totient is φ = 200960.

The previous prime is 640967. The next prime is 640973. The reversal of 640968 is 869046.

640968 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (640963) 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, 378 + ... + 1193.

It is an arithmetic number, because the mean of its divisors is an integer number (53055).

2⁶⁴⁰⁹⁶⁸ is an apocalyptic number.

640968 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

640968 is an abundant number, since it is smaller than the sum of its proper divisors (1056792).

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

640968 is a wasteful number, since it uses less digits than its factorization.

640968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1597 (or 1593 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 640968 is about 800.6047714072. The cubic root of 640968 is about 86.2208134810.

The spelling of 640968 in words is "six hundred forty thousand, nine hundred sixty-eight".