644838313 has 16 divisors (see below), whose sum is σ = 744802560. Its totient is φ = 546863616.

The previous prime is 644838301. The next prime is 644838323. The reversal of 644838313 is 313838446.

It is a cyclic number.

It is not a de Polignac number, because 644838313 - 2²¹ = 642741161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644838323) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 343345 + ... + 345217.

It is an arithmetic number, because the mean of its divisors is an integer number (46550160).

Almost surely, 2^644838313 is an apocalyptic number.

It is an amenable number.

644838313 is a deficient number, since it is larger than the sum of its proper divisors (99964247).

644838313 is a wasteful number, since it uses less digits than its factorization.

644838313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2376.

The product of its digits is 165888, while the sum is 40.

The square root of 644838313 is about 25393.6667891819. Note that the first 3 decimals coincide. The cubic root of 644838313 is about 863.9400575877.

The spelling of 644838313 in words is "six hundred forty-four million, eight hundred thirty-eight thousand, three hundred thirteen".