644004745 has 4 divisors (see below), whose sum is σ = 772805700. Its totient is φ = 515203792.

The previous prime is 644004733. The next prime is 644004773. The reversal of 644004745 is 547400446.

644004745 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 425349376 + 218655369 = 20624^2 + 14787^2 .

It is a cyclic number.

It is not a de Polignac number, because 644004745 - 2⁷ = 644004617 is a prime.

It is a super-2 number, since 2×644004745² = 829484223165030050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644004745.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64400470 + ... + 64400479.

It is an arithmetic number, because the mean of its divisors is an integer number (193201425).

Almost surely, 2^644004745 is an apocalyptic number.

It is an amenable number.

644004745 is a deficient number, since it is larger than the sum of its proper divisors (128800955).

644004745 is a wasteful number, since it uses less digits than its factorization.

644004745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128800954.

The product of its (nonzero) digits is 53760, while the sum is 34.

The square root of 644004745 is about 25377.2485703238. The cubic root of 644004745 is about 863.5676317651.

The spelling of 644004745 in words is "six hundred forty-four million, four thousand, seven hundred forty-five".