644440313 has 6 divisors (see below), whose sum is σ = 708351882. Its totient is φ = 585854720.

The previous prime is 644440253. The next prime is 644440327. The reversal of 644440313 is 313044446.

644440313 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 only one way, i.e., 540237049 + 104203264 = 23243^2 + 10208^2 .

It is not a de Polignac number, because 644440313 - 2⁶ = 644440249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644440343) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2662856 + ... + 2663097.

It is an arithmetic number, because the mean of its divisors is an integer number (118058647).

Almost surely, 2^644440313 is an apocalyptic number.

It is an amenable number.

644440313 is a deficient number, since it is larger than the sum of its proper divisors (63911569).

644440313 is a wasteful number, since it uses less digits than its factorization.

644440313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5325975 (or 5325964 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 644440313 is about 25385.8289799644. The cubic root of 644440313 is about 863.7622771517.

Adding to 644440313 its reverse (313044446), we get a palindrome (957484759).

The spelling of 644440313 in words is "six hundred forty-four million, four hundred forty thousand, three hundred thirteen".