644638337 has 4 divisors (see below), whose sum is σ = 736729536. Its totient is φ = 552547140.

The previous prime is 644638333. The next prime is 644638349. The reversal of 644638337 is 733836446.

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 644638337 - 2² = 644638333 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644638333) 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, 46045589 + ... + 46045602.

It is an arithmetic number, because the mean of its divisors is an integer number (184182384).

Almost surely, 2^644638337 is an apocalyptic number.

It is an amenable number.

644638337 is a deficient number, since it is larger than the sum of its proper divisors (92091199).

644638337 is an equidigital number, since it uses as much as digits as its factorization.

644638337 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92091198.

The product of its digits is 870912, while the sum is 44.

The square root of 644638337 is about 25389.7289666511. The cubic root of 644638337 is about 863.8507405522.

The spelling of 644638337 in words is "six hundred forty-four million, six hundred thirty-eight thousand, three hundred thirty-seven".