644635413 has 12 divisors (see below), whose sum is σ = 934766508. Its totient is φ = 428083200.

The previous prime is 644635399. The next prime is 644635451. The reversal of 644635413 is 314536446.

644635413 is a `hidden beast` number, since 6 + 4 + 4 + 635 + 4 + 13 = 666.

644635413 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 630662769 + 13972644 = 25113^2 + 3738^2 .

It is a de Polignac number, because none of the positive numbers 2^k-644635413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644635493) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 137038 + ... + 141663.

It is an arithmetic number, because the mean of its divisors is an integer number (77897209).

Almost surely, 2^644635413 is an apocalyptic number.

It is an amenable number.

644635413 is a deficient number, since it is larger than the sum of its proper divisors (290131095).

644635413 is a wasteful number, since it uses less digits than its factorization.

644635413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278964 (or 278961 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The square root of 644635413 is about 25389.6713842460. The cubic root of 644635413 is about 863.8494344434.

The spelling of 644635413 in words is "six hundred forty-four million, six hundred thirty-five thousand, four hundred thirteen".