644163009 has 8 divisors (see below), whose sum is σ = 981581760. Its totient is φ = 368093136.

The previous prime is 644162999. The next prime is 644163017. The reversal of 644163009 is 900361446.

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

It is not a de Polignac number, because 644163009 - 2⁵ = 644162977 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644163089) 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, 15337194 + ... + 15337235.

It is an arithmetic number, because the mean of its divisors is an integer number (122697720).

Almost surely, 2^644163009 is an apocalyptic number.

It is an amenable number.

644163009 is a deficient number, since it is larger than the sum of its proper divisors (337418751).

644163009 is a wasteful number, since it uses less digits than its factorization.

644163009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30674439.

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 644163009 is about 25380.3666049173. The cubic root of 644163009 is about 863.6383664787.

The spelling of 644163009 in words is "six hundred forty-four million, one hundred sixty-three thousand, nine".