640696 has 32 divisors (see below), whose sum is σ = 1455840. Its totient is φ = 258048.

The previous prime is 640691. The next prime is 640727. The reversal of 640696 is 696046.

640696 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640691) 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, 616 + ... + 1288.

It is an arithmetic number, because the mean of its divisors is an integer number (45495).

2⁶⁴⁰⁶⁹⁶ 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 640696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (727920).

640696 is an abundant number, since it is smaller than the sum of its proper divisors (815144).

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

640696 is a wasteful number, since it uses less digits than its factorization.

640696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 703 (or 699 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 640696 is about 800.4348817986. The cubic root of 640696 is about 86.2086155869.

The spelling of 640696 in words is "six hundred forty thousand, six hundred ninety-six".