640686902 has 8 divisors (see below), whose sum is σ = 961372800. Its totient is φ = 320229304.

The previous prime is 640686901. The next prime is 640686911. The reversal of 640686902 is 209686046.

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

It is a self number, because there is not a number n which added to its sum of digits gives 640686902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640686901) 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 3 ways as a sum of consecutive naturals, for example, 49877 + ... + 61392.

It is an arithmetic number, because the mean of its divisors is an integer number (120171600).

Almost surely, 2^640686902 is an apocalyptic number.

640686902 is a deficient number, since it is larger than the sum of its proper divisors (320685898).

640686902 is a wasteful number, since it uses less digits than its factorization.

640686902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114150.

The product of its (nonzero) digits is 124416, while the sum is 41.

The square root of 640686902 is about 25311.7937333568. The cubic root of 640686902 is about 862.0820752559.

The spelling of 640686902 in words is "six hundred forty million, six hundred eighty-six thousand, nine hundred two".