644383445 has 4 divisors (see below), whose sum is σ = 773260140. Its totient is φ = 515506752.

The previous prime is 644383357. The next prime is 644383447. The reversal of 644383445 is 544383446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 544383446 = 2 ⋅272191723.

It can be written as a sum of positive squares in 2 ways, for example, as 370216081 + 274167364 = 19241^2 + 16558^2 .

It is a cyclic number.

It is not a de Polignac number, because 644383445 - 2¹⁶ = 644317909 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644383447) 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 3 ways as a sum of consecutive naturals, for example, 64438340 + ... + 64438349.

It is an arithmetic number, because the mean of its divisors is an integer number (193315035).

Almost surely, 2^644383445 is an apocalyptic number.

It is an amenable number.

644383445 is a deficient number, since it is larger than the sum of its proper divisors (128876695).

644383445 is a wasteful number, since it uses less digits than its factorization.

644383445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128876694.

The product of its digits is 552960, while the sum is 41.

The square root of 644383445 is about 25384.7088815294. The cubic root of 644383445 is about 863.7368691208.

Subtracting from 644383445 its reverse (544383446), we obtain a palindrome (99999999).

The spelling of 644383445 in words is "six hundred forty-four million, three hundred eighty-three thousand, four hundred forty-five".