640720268 has 12 divisors (see below), whose sum is σ = 1151565072. Its totient is φ = 311701680.

The previous prime is 640720217. The next prime is 640720273. The reversal of 640720268 is 862027046.

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, 2164448 + ... + 2164743.

It is an arithmetic number, because the mean of its divisors is an integer number (95963756).

Almost surely, 2^640720268 is an apocalyptic number.

It is an amenable number.

640720268 is a deficient number, since it is larger than the sum of its proper divisors (510844804).

640720268 is a wasteful number, since it uses less digits than its factorization.

640720268 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4329232 (or 4329230 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 640720268 is about 25312.4528246474. The cubic root of 640720268 is about 862.0970403041.

The spelling of 640720268 in words is "six hundred forty million, seven hundred twenty thousand, two hundred sixty-eight".