644941609 has 8 divisors (see below), whose sum is σ = 696819200. Its totient is φ = 593387856.

The previous prime is 644941601. The next prime is 644941613. The reversal of 644941609 is 906149446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644941609 - 2³ = 644941601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644941601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76809 + ... + 84790.

It is an arithmetic number, because the mean of its divisors is an integer number (87102400).

Almost surely, 2^644941609 is an apocalyptic number.

It is an amenable number.

644941609 is a deficient number, since it is larger than the sum of its proper divisors (51877591).

644941609 is a wasteful number, since it uses less digits than its factorization.

644941609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161919.

The product of its (nonzero) digits is 186624, while the sum is 43.

The square root of 644941609 is about 25395.7006006922. The cubic root of 644941609 is about 863.9861863539.

The spelling of 644941609 in words is "six hundred forty-four million, nine hundred forty-one thousand, six hundred nine".