640632 has 16 divisors (see below), whose sum is σ = 1601640. Its totient is φ = 213536.

The previous prime is 640631. The next prime is 640649. The reversal of 640632 is 236046.

640632 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 640599 and 640608.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640632.

It is not an unprimeable number, because it can be changed into a prime (640631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13323 + ... + 13370.

2⁶⁴⁰⁶³² is an apocalyptic number.

It is an amenable number.

640632 is an abundant number, since it is smaller than the sum of its proper divisors (961008).

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

640632 is a wasteful number, since it uses less digits than its factorization.

640632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26702 (or 26698 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 640632 is about 800.3949025325. The cubic root of 640632 is about 86.2057449924.

Adding to 640632 its reverse (236046), we get a palindrome (876678).

The spelling of 640632 in words is "six hundred forty thousand, six hundred thirty-two".