640267856 has 20 divisors (see below), whose sum is σ = 1249578132. Its totient is φ = 317796096.

The previous prime is 640267811. The next prime is 640267867. The reversal of 640267856 is 658762046.

It can be written as a sum of positive squares in 2 ways, for example, as 199939600 + 440328256 = 14140^2 + 20984^2 .

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

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, 143855 + ... + 148238.

Almost surely, 2^640267856 is an apocalyptic number.

It is an amenable number.

640267856 is a deficient number, since it is larger than the sum of its proper divisors (609310276).

640267856 is a wasteful number, since it uses less digits than its factorization.

640267856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292238 (or 292232 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 44.

The square root of 640267856 is about 25303.5146965792. The cubic root of 640267856 is about 861.8940838815.

The spelling of 640267856 in words is "six hundred forty million, two hundred sixty-seven thousand, eight hundred fifty-six".