644308943 has 4 divisors (see below), whose sum is σ = 678219960. Its totient is φ = 610397928.

The previous prime is 644308939. The next prime is 644308961. The reversal of 644308943 is 349803446.

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 644308943 - 2² = 644308939 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 644308943.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644308043) 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, 16955480 + ... + 16955517.

It is an arithmetic number, because the mean of its divisors is an integer number (169554990).

Almost surely, 2^644308943 is an apocalyptic number.

644308943 is a deficient number, since it is larger than the sum of its proper divisors (33911017).

644308943 is a wasteful number, since it uses less digits than its factorization.

644308943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33911016.

The product of its (nonzero) digits is 248832, while the sum is 41.

The square root of 644308943 is about 25383.2413808796. The cubic root of 644308943 is about 863.7035801400.

The spelling of 644308943 in words is "six hundred forty-four million, three hundred eight thousand, nine hundred forty-three".