644535443 has 4 divisors (see below), whose sum is σ = 644625240. Its totient is φ = 644445648.

The previous prime is 644535431. The next prime is 644535473. The reversal of 644535443 is 344535446.

644535443 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644535443 - 2⁴ = 644535427 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644535397 and 644535406.

It is not an unprimeable number, because it can be changed into a prime (644535403) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33098 + ... + 48831.

It is an arithmetic number, because the mean of its divisors is an integer number (161156310).

Almost surely, 2^644535443 is an apocalyptic number.

644535443 is a deficient number, since it is larger than the sum of its proper divisors (89797).

644535443 is an equidigital number, since it uses as much as digits as its factorization.

644535443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89796.

The product of its digits is 345600, while the sum is 38.

The square root of 644535443 is about 25387.7025939725. The cubic root of 644535443 is about 863.8047769048.

It can be divided in two parts, 64453 and 5443, that added together give a palindrome (69896).

The spelling of 644535443 in words is "six hundred forty-four million, five hundred thirty-five thousand, four hundred forty-three".