646758644 has 18 divisors (see below), whose sum is σ = 1316616210. Its totient is φ = 277182192.

The previous prime is 646758577. The next prime is 646758691. The reversal of 646758644 is 446857646.

It can be written as a sum of positive squares in only one way, i.e., 594774544 + 51984100 = 24388^2 + 7210^2 .

It is a junction number, because it is equal to n+sod(n) for n = 646758592 and 646758601.

It is a congruent number.

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 5 ways as a sum of consecutive naturals, for example, 1649699 + ... + 1650090.

It is an arithmetic number, because the mean of its divisors is an integer number (73145345).

Almost surely, 2^646758644 is an apocalyptic number.

It is an amenable number.

646758644 is an abundant number, since it is smaller than the sum of its proper divisors (669857566).

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

646758644 is a wasteful number, since it uses less digits than its factorization.

646758644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3299807 (or 3299798 counting only the distinct ones).

The product of its digits is 3870720, while the sum is 50.

The square root of 646758644 is about 25431.4498996813. The cubic root of 646758644 is about 864.7968132911.

The spelling of 646758644 in words is "six hundred forty-six million, seven hundred fifty-eight thousand, six hundred forty-four".