640686683 has 8 divisors (see below), whose sum is σ = 788537568. Its totient is φ = 506916864.

The previous prime is 640686653. The next prime is 640686719. The reversal of 640686683 is 386686046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640686683 - 2⁶ = 640686619 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640686653) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 3520166 + ... + 3520347.

It is an arithmetic number, because the mean of its divisors is an integer number (98567196).

Almost surely, 2^640686683 is an apocalyptic number.

640686683 is a deficient number, since it is larger than the sum of its proper divisors (147850885).

640686683 is a wasteful number, since it uses less digits than its factorization.

640686683 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7040533.

The product of its (nonzero) digits is 995328, while the sum is 47.

The square root of 640686683 is about 25311.7894073098. The cubic root of 640686683 is about 862.0819770300.

The spelling of 640686683 in words is "six hundred forty million, six hundred eighty-six thousand, six hundred eighty-three".