640832 has 56 divisors (see below), whose sum is σ = 1463040. Its totient is φ = 276480.

The previous prime is 640793. The next prime is 640837. The reversal of 640832 is 238046.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 640798 and 640807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640837) 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, 20657 + ... + 20687.

2⁶⁴⁰⁸³² is an apocalyptic number.

640832 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640832, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (731520).

640832 is an abundant number, since it is smaller than the sum of its proper divisors (822208).

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

640832 is a wasteful number, since it uses less digits than its factorization.

640832 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79 (or 69 counting only the distinct ones).

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

The square root of 640832 is about 800.5198311098. The cubic root of 640832 is about 86.2147149654.

Adding to 640832 its reverse (238046), we get a palindrome (878878).

The spelling of 640832 in words is "six hundred forty thousand, eight hundred thirty-two".