644409016 has 16 divisors (see below), whose sum is σ = 1271860200. Its totient is φ = 305246304.

The previous prime is 644408939. The next prime is 644409037. The reversal of 644409016 is 610904446.

644409016 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2119615 + ... + 2119918.

Almost surely, 2^644409016 is an apocalyptic number.

It is an amenable number.

644409016 is a deficient number, since it is larger than the sum of its proper divisors (627451184).

644409016 is a wasteful number, since it uses less digits than its factorization.

644409016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4239558 (or 4239554 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 644409016 is about 25385.2125458898. The cubic root of 644409016 is about 863.7482941626.

The spelling of 644409016 in words is "six hundred forty-four million, four hundred nine thousand, sixteen".