640220 has 48 divisors (see below), whose sum is σ = 1632960. Its totient is φ = 205824.

The previous prime is 640219. The next prime is 640223. The reversal of 640220 is 22046.

640220 = 186² + 187² + ... + 202².

640220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a junction number, because it is equal to n+sod(n) for n = 640195 and 640204.

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 640220.

It is not an unprimeable number, because it can be changed into a prime (640223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2246 + ... + 2514.

It is an arithmetic number, because the mean of its divisors is an integer number (34020).

2⁶⁴⁰²²⁰ 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 640220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (816480).

640220 is an abundant number, since it is smaller than the sum of its proper divisors (992740).

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

640220 is a wasteful number, since it uses less digits than its factorization.

640220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302 (or 300 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 640220 is about 800.1374881856. The cubic root of 640220 is about 86.1872609624.

Adding to 640220 its reverse (22046), we get a palindrome (662266).

The spelling of 640220 in words is "six hundred forty thousand, two hundred twenty".