644804438 has 8 divisors (see below), whose sum is σ = 967500288. Its totient is φ = 322304344.

The previous prime is 644804437. The next prime is 644804491. The reversal of 644804438 is 834408446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 644804395 and 644804404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644804431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40406 + ... + 54057.

It is an arithmetic number, because the mean of its divisors is an integer number (120937536).

Almost surely, 2^644804438 is an apocalyptic number.

644804438 is a deficient number, since it is larger than the sum of its proper divisors (322695850).

644804438 is a wasteful number, since it uses less digits than its factorization.

644804438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97878.

The product of its (nonzero) digits is 294912, while the sum is 41.

The square root of 644804438 is about 25392.9997834049. Note that the first 3 decimals coincide. The cubic root of 644804438 is about 863.9249289984.

The spelling of 644804438 in words is "six hundred forty-four million, eight hundred four thousand, four hundred thirty-eight".