640255220 has 24 divisors (see below), whose sum is σ = 1466767008. Its totient is φ = 232820000.

The previous prime is 640255219. The next prime is 640255223. The reversal of 640255220 is 22552046.

It is a self number, because there is not a number n which added to its sum of digits gives 640255220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640255223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1454906 + ... + 1455345.

It is an arithmetic number, because the mean of its divisors is an integer number (61115292).

Almost surely, 2^640255220 is an apocalyptic number.

It is an amenable number.

640255220 is an abundant number, since it is smaller than the sum of its proper divisors (826511788).

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

640255220 is a wasteful number, since it uses less digits than its factorization.

640255220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2910271 (or 2910269 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 26.

The square root of 640255220 is about 25303.2650067141. The cubic root of 640255220 is about 861.8884138767. Note that the first 3 decimals are identical.

The spelling of 640255220 in words is "six hundred forty million, two hundred fifty-five thousand, two hundred twenty".