644343890 has 16 divisors (see below), whose sum is σ = 1166937408. Its totient is φ = 256155696.

The previous prime is 644343881. The next prime is 644343893. The reversal of 644343890 is 98343446.

644343890 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644343893) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 196022 + ... + 199281.

It is an arithmetic number, because the mean of its divisors is an integer number (72933588).

Almost surely, 2^644343890 is an apocalyptic number.

644343890 is a deficient number, since it is larger than the sum of its proper divisors (522593518).

644343890 is a wasteful number, since it uses less digits than its factorization.

644343890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395473.

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

The square root of 644343890 is about 25383.9297588061. The cubic root of 644343890 is about 863.7191954768.

The spelling of 644343890 in words is "six hundred forty-four million, three hundred forty-three thousand, eight hundred ninety".