644464729 has 4 divisors (see below), whose sum is σ = 655387920. Its totient is φ = 633541540.

The previous prime is 644464727. The next prime is 644464757. The reversal of 644464729 is 927464446.

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 644464729 - 2¹ = 644464727 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644464721) 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 3 ways as a sum of consecutive naturals, for example, 5461507 + ... + 5461624.

It is an arithmetic number, because the mean of its divisors is an integer number (163846980).

Almost surely, 2^644464729 is an apocalyptic number.

It is an amenable number.

644464729 is a deficient number, since it is larger than the sum of its proper divisors (10923191).

644464729 is a wasteful number, since it uses less digits than its factorization.

644464729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10923190.

The product of its digits is 1161216, while the sum is 46.

The square root of 644464729 is about 25386.3098736307. The cubic root of 644464729 is about 863.7731855079.

The spelling of 644464729 in words is "six hundred forty-four million, four hundred sixty-four thousand, seven hundred twenty-nine".