646839685 has 16 divisors (see below), whose sum is σ = 784589040. Its totient is φ = 511902720.

The previous prime is 646839659. The next prime is 646839733. The reversal of 646839685 is 586938646.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 89832484 + 557007201 = 9478^2 + 23601^2 .

It is not a de Polignac number, because 646839685 - 2¹¹ = 646837637 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 467695 + ... + 469075.

It is an arithmetic number, because the mean of its divisors is an integer number (49036815).

Almost surely, 2^646839685 is an apocalyptic number.

It is an amenable number.

646839685 is a deficient number, since it is larger than the sum of its proper divisors (137749355).

646839685 is a wasteful number, since it uses less digits than its factorization.

646839685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2328.

The product of its digits is 7464960, while the sum is 55.

The square root of 646839685 is about 25433.0431722199. The cubic root of 646839685 is about 864.8329324174.

The spelling of 646839685 in words is "six hundred forty-six million, eight hundred thirty-nine thousand, six hundred eighty-five".