640664634 has 16 divisors (see below), whose sum is σ = 1285135488. Its totient is φ = 212920512.

The previous prime is 640664621. The next prime is 640664659. The reversal of 640664634 is 436466046.

640664634 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 640664592 and 640664601.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156402 + ... + 160445.

It is an arithmetic number, because the mean of its divisors is an integer number (80320968).

Almost surely, 2^640664634 is an apocalyptic number.

640664634 is an abundant number, since it is smaller than the sum of its proper divisors (644470854).

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

640664634 is a wasteful number, since it uses less digits than its factorization.

640664634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317189.

The product of its (nonzero) digits is 248832, while the sum is 39.

The square root of 640664634 is about 25311.3538555329. The cubic root of 640664634 is about 862.0720875037.

The spelling of 640664634 in words is "six hundred forty million, six hundred sixty-four thousand, six hundred thirty-four".