640558420 has 12 divisors (see below), whose sum is σ = 1345172724. Its totient is φ = 256223360.

The previous prime is 640558417. The next prime is 640558423. The reversal of 640558420 is 24855046.

It is an interprime number because it is at equal distance from previous prime (640558417) and next prime (640558423).

It can be written as a sum of positive squares in 2 ways, for example, as 391802436 + 248755984 = 19794^2 + 15772^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640558423) 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 3 ways as a sum of consecutive naturals, for example, 16013941 + ... + 16013980.

It is an arithmetic number, because the mean of its divisors is an integer number (112097727).

Almost surely, 2^640558420 is an apocalyptic number.

It is an amenable number.

640558420 is an abundant number, since it is smaller than the sum of its proper divisors (704614304).

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

640558420 is a wasteful number, since it uses less digits than its factorization.

640558420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32027930 (or 32027928 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 34.

The square root of 640558420 is about 25309.2556192394. The cubic root of 640558420 is about 862.0244446963.

The spelling of 640558420 in words is "six hundred forty million, five hundred fifty-eight thousand, four hundred twenty".