644016909 has 16 divisors (see below), whose sum is σ = 887169024. Its totient is φ = 415129200.

The previous prime is 644016907. The next prime is 644016911. The reversal of 644016909 is 909610446.

644016909 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (644016907) and next prime (644016911).

It is not a de Polignac number, because 644016909 - 2¹ = 644016907 is a prime.

It is a super-3 number, since 3×644016909³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644016907) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 138232 + ... + 142814.

It is an arithmetic number, because the mean of its divisors is an integer number (55448064).

Almost surely, 2^644016909 is an apocalyptic number.

It is an amenable number.

644016909 is a deficient number, since it is larger than the sum of its proper divisors (243152115).

644016909 is a wasteful number, since it uses less digits than its factorization.

644016909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6128.

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 644016909 is about 25377.4882326837. The cubic root of 644016909 is about 863.5730687699.

The spelling of 644016909 in words is "six hundred forty-four million, sixteen thousand, nine hundred nine".