644530009 has 4 divisors (see below), whose sum is σ = 644790016. Its totient is φ = 644270004.

The previous prime is 644530001. The next prime is 644530013. The reversal of 644530009 is 900035446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644530009 - 2³ = 644530001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644530001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126249 + ... + 131254.

It is an arithmetic number, because the mean of its divisors is an integer number (161197504).

Almost surely, 2^644530009 is an apocalyptic number.

It is an amenable number.

644530009 is a deficient number, since it is larger than the sum of its proper divisors (260007).

644530009 is a wasteful number, since it uses less digits than its factorization.

644530009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260006.

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 644530009 is about 25387.5955734292. The cubic root of 644530009 is about 863.8023493536.

The spelling of 644530009 in words is "six hundred forty-four million, five hundred thirty thousand, nine".