644646441 has 8 divisors (see below), whose sum is σ = 863982880. Its totient is φ = 427537152.

The previous prime is 644646439. The next prime is 644646451. The reversal of 644646441 is 144646446.

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

It is not a de Polignac number, because 644646441 - 2¹ = 644646439 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644646441.

It is not an unprimeable number, because it can be changed into a prime (644646451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 556111 + ... + 557268.

It is an arithmetic number, because the mean of its divisors is an integer number (107997860).

Almost surely, 2^644646441 is an apocalyptic number.

It is an amenable number.

644646441 is a deficient number, since it is larger than the sum of its proper divisors (219336439).

644646441 is a wasteful number, since it uses less digits than its factorization.

644646441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1113575.

The product of its digits is 221184, while the sum is 39.

The square root of 644646441 is about 25389.8885582430. Note that the first 3 decimals coincide. The cubic root of 644646441 is about 863.8543604719.

The spelling of 644646441 in words is "six hundred forty-four million, six hundred forty-six thousand, four hundred forty-one".