644969043 has 24 divisors (see below), whose sum is σ = 977465216. Its totient is φ = 409276800.

The previous prime is 644969029. The next prime is 644969063. The reversal of 644969043 is 340969446.

It is a happy number.

644969043 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644969043 - 2¹⁰ = 644968019 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644969043.

It is not an unprimeable number, because it can be changed into a prime (644969063) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1930 + ... + 35967.

Almost surely, 2^644969043 is an apocalyptic number.

644969043 is a deficient number, since it is larger than the sum of its proper divisors (332496173).

644969043 is a wasteful number, since it uses less digits than its factorization.

644969043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37995 (or 37992 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 45.

The square root of 644969043 is about 25396.2407257452. The cubic root of 644969043 is about 863.9984366934.

The spelling of 644969043 in words is "six hundred forty-four million, nine hundred sixty-nine thousand, forty-three".