640228 has 12 divisors (see below), whose sum is σ = 1169280. Its totient is φ = 306152.

The previous prime is 640223. The next prime is 640229. The reversal of 640228 is 822046.

It is a junction number, because it is equal to n+sod(n) for n = 640199 and 640208.

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 3 ways as a sum of consecutive naturals, for example, 3388 + ... + 3571.

It is an arithmetic number, because the mean of its divisors is an integer number (97440).

2⁶⁴⁰²²⁸ is an apocalyptic number.

It is an amenable number.

640228 is a deficient number, since it is larger than the sum of its proper divisors (529052).

640228 is a wasteful number, since it uses less digits than its factorization.

640228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6986 (or 6984 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 640228 is about 800.1424873109. The cubic root of 640228 is about 86.1876199511.

It can be divided in two parts, 640 and 228, that added together give a palindrome (868).

The spelling of 640228 in words is "six hundred forty thousand, two hundred twenty-eight".