644535564443 has 4 divisors (see below), whose sum is σ = 645109506408. Its totient is φ = 643961622480.

The previous prime is 644535564401. The next prime is 644535564457. The reversal of 644535564443 is 344465535446.

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 644535564443 - 2³⁴ = 627355695259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644535564943) 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, 286969298 + ... + 286971543.

It is an arithmetic number, because the mean of its divisors is an integer number (161277376602).

Almost surely, 2^644535564443 is an apocalyptic number.

644535564443 is a deficient number, since it is larger than the sum of its proper divisors (573941965).

644535564443 is a wasteful number, since it uses less digits than its factorization.

644535564443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573941964.

The product of its digits is 41472000, while the sum is 53.

The spelling of 644535564443 in words is "six hundred forty-four billion, five hundred thirty-five million, five hundred sixty-four thousand, four hundred forty-three".