644116213 has 8 divisors (see below), whose sum is σ = 734467608. Its totient is φ = 559593984.

The previous prime is 644116201. The next prime is 644116217. The reversal of 644116213 is 312611446.

It can be written as a sum of positive squares in 4 ways, for example, as 5391684 + 638724529 = 2322^2 + 25273^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644116213 - 2⁹ = 644115701 is a prime.

It is a super-2 number, since 2×644116213² = 829771391698922738, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644116217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1457056 + ... + 1457497.

It is an arithmetic number, because the mean of its divisors is an integer number (91808451).

Almost surely, 2^644116213 is an apocalyptic number.

It is an amenable number.

644116213 is a deficient number, since it is larger than the sum of its proper divisors (90351395).

644116213 is a wasteful number, since it uses less digits than its factorization.

644116213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2914583.

The product of its digits is 3456, while the sum is 28.

The square root of 644116213 is about 25379.4446944767. Note that the first 3 decimals coincide. The cubic root of 644116213 is about 863.6174526214.

Adding to 644116213 its reverse (312611446), we get a palindrome (956727659).

The spelling of 644116213 in words is "six hundred forty-four million, one hundred sixteen thousand, two hundred thirteen".