644453543 has 4 divisors (see below), whose sum is σ = 646731048. Its totient is φ = 642176040.

The previous prime is 644453489. The next prime is 644453587. The reversal of 644453543 is 345354446.

644453543 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 a de Polignac number, because none of the positive numbers 2^k-644453543 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644453497 and 644453506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644453743) 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, 1138328 + ... + 1138893.

It is an arithmetic number, because the mean of its divisors is an integer number (161682762).

Almost surely, 2^644453543 is an apocalyptic number.

644453543 is a deficient number, since it is larger than the sum of its proper divisors (2277505).

644453543 is a wasteful number, since it uses less digits than its factorization.

644453543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2277504.

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

The square root of 644453543 is about 25386.0895570783. The cubic root of 644453543 is about 863.7681879638.

The spelling of 644453543 in words is "six hundred forty-four million, four hundred fifty-three thousand, five hundred forty-three".