644646447 has 6 divisors (see below), whose sum is σ = 931155992. Its totient is φ = 429764292.

The previous prime is 644646439. The next prime is 644646451. The reversal of 644646447 is 744646446.

644646447 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644646447 - 2³ = 644646439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644646427) 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, 35813683 + ... + 35813700.

Almost surely, 2^644646447 is an apocalyptic number.

644646447 is a deficient number, since it is larger than the sum of its proper divisors (286509545).

644646447 is a wasteful number, since it uses less digits than its factorization.

644646447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71627389 (or 71627386 counting only the distinct ones).

The product of its digits is 1548288, while the sum is 45.

The square root of 644646447 is about 25389.8886764003. Note that the first 3 decimals coincide. The cubic root of 644646447 is about 863.8543631520.

Subtracting 644646447 from its reverse (744646446), we obtain a palindrome (99999999).

The spelling of 644646447 in words is "six hundred forty-four million, six hundred forty-six thousand, four hundred forty-seven".