640273808 has 10 divisors (see below), whose sum is σ = 1240530534. Its totient is φ = 320136896.

The previous prime is 640273787. The next prime is 640273813. The reversal of 640273808 is 808372046.

It can be written as a sum of positive squares in only one way, i.e., 501222544 + 139051264 = 22388^2 + 11792^2 .

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 as a sum of consecutive naturals, namely, 20008541 + ... + 20008572.

Almost surely, 2^640273808 is an apocalyptic number.

It is an amenable number.

640273808 is a deficient number, since it is larger than the sum of its proper divisors (600256726).

640273808 is a wasteful number, since it uses less digits than its factorization.

640273808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40017121 (or 40017115 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 38.

The square root of 640273808 is about 25303.6323084256. The cubic root of 640273808 is about 861.8967546271.

The spelling of 640273808 in words is "six hundred forty million, two hundred seventy-three thousand, eight hundred eight".