640328 has 32 divisors (see below), whose sum is σ = 1330560. Its totient is φ = 287040.

The previous prime is 640307. The next prime is 640333. The reversal of 640328 is 823046.

It is a happy number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640328.

It is an unprimeable number.

640328 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4823 + ... + 4953.

It is an arithmetic number, because the mean of its divisors is an integer number (41580).

2⁶⁴⁰³²⁸ 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 640328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (665280).

640328 is an abundant number, since it is smaller than the sum of its proper divisors (690232).

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

640328 is a wasteful number, since it uses less digits than its factorization.

640328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197 (or 193 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 640328 is about 800.2049737411. The cubic root of 640328 is about 86.1921070574.

The spelling of 640328 in words is "six hundred forty thousand, three hundred twenty-eight".