644747329 has 4 divisors (see below), whose sum is σ = 645272320. Its totient is φ = 644222340.

The previous prime is 644747309. The next prime is 644747333. The reversal of 644747329 is 923747446.

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 644747329 - 2¹⁵ = 644714561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644747309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260649 + ... + 263110.

It is an arithmetic number, because the mean of its divisors is an integer number (161318080).

Almost surely, 2^644747329 is an apocalyptic number.

It is an amenable number.

644747329 is a deficient number, since it is larger than the sum of its proper divisors (524991).

644747329 is a wasteful number, since it uses less digits than its factorization.

644747329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524990.

The product of its digits is 1016064, while the sum is 46.

The square root of 644747329 is about 25391.8752556797. The cubic root of 644747329 is about 863.8994228953.

The spelling of 644747329 in words is "six hundred forty-four million, seven hundred forty-seven thousand, three hundred twenty-nine".