640218 has 8 divisors (see below), whose sum is σ = 1280448. Its totient is φ = 213404.

The previous prime is 640193. The next prime is 640219. The reversal of 640218 is 812046.

640218 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

640218 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 640194 and 640203.

It is not an unprimeable number, because it can be changed into a prime (640219) by changing a digit.

640218 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 3 ways as a sum of consecutive naturals, for example, 53346 + ... + 53357.

It is an arithmetic number, because the mean of its divisors is an integer number (160056).

2⁶⁴⁰²¹⁸ is an apocalyptic number.

640218 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

640218 is a wasteful number, since it uses less digits than its factorization.

640218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106708.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 640218 is about 800.1362383994. The cubic root of 640218 is about 86.1871712147.

It can be divided in two parts, 640 and 218, that added together give a palindrome (858).

The spelling of 640218 in words is "six hundred forty thousand, two hundred eighteen".