646605640 has 32 divisors (see below), whose sum is σ = 1455613560. Its totient is φ = 258508800.

The previous prime is 646605637. The next prime is 646605689. The reversal of 646605640 is 46506646.

It can be written as a sum of positive squares in 4 ways, for example, as 554790916 + 91814724 = 23554^2 + 9582^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 646605640.

It is an unprimeable number.

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, 119800 + ... + 125080.

Almost surely, 2^646605640 is an apocalyptic number.

It is an amenable number.

646605640 is an abundant number, since it is smaller than the sum of its proper divisors (809007920).

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

646605640 is a wasteful number, since it uses less digits than its factorization.

646605640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8353 (or 8349 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 37.

The square root of 646605640 is about 25428.4415566507. The cubic root of 646605640 is about 864.7286127816.

The spelling of 646605640 in words is "six hundred forty-six million, six hundred five thousand, six hundred forty".