640205 has 16 divisors (see below), whose sum is σ = 846720. Its totient is φ = 462528.

The previous prime is 640193. The next prime is 640219. The reversal of 640205 is 502046.

640205 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 640205 - 2⁸ = 639949 is a prime.

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 640205.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2039 + ... + 2331.

It is an arithmetic number, because the mean of its divisors is an integer number (52920).

2⁶⁴⁰²⁰⁵ is an apocalyptic number.

It is an amenable number.

640205 is a deficient number, since it is larger than the sum of its proper divisors (206515).

640205 is a wasteful number, since it uses less digits than its factorization.

640205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 640205 is about 800.1281147416. The cubic root of 640205 is about 86.1865878505.

The spelling of 640205 in words is "six hundred forty thousand, two hundred five".