640779902 has 32 divisors (see below), whose sum is σ = 1170969600. Its totient is φ = 256864608.

The previous prime is 640779901. The next prime is 640779907. The reversal of 640779902 is 209977046.

640779902 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640779901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5768 + ... + 36260.

It is an arithmetic number, because the mean of its divisors is an integer number (36592800).

Almost surely, 2^640779902 is an apocalyptic number.

640779902 is a deficient number, since it is larger than the sum of its proper divisors (530189698).

640779902 is a wasteful number, since it uses less digits than its factorization.

640779902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30600.

The product of its (nonzero) digits is 190512, while the sum is 44.

The square root of 640779902 is about 25313.6307549905. The cubic root of 640779902 is about 862.1237855691.

The spelling of 640779902 in words is "six hundred forty million, seven hundred seventy-nine thousand, nine hundred two".