644338798 has 4 divisors (see below), whose sum is σ = 966508200. Its totient is φ = 322169398.

The previous prime is 644338787. The next prime is 644338817. The reversal of 644338798 is 897833446.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161084698 + ... + 161084701.

It is an arithmetic number, because the mean of its divisors is an integer number (241627050).

Almost surely, 2^644338798 is an apocalyptic number.

644338798 is a deficient number, since it is larger than the sum of its proper divisors (322169402).

644338798 is a wasteful number, since it uses less digits than its factorization.

644338798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322169401.

The product of its digits is 3483648, while the sum is 52.

The square root of 644338798 is about 25383.8294589292. The cubic root of 644338798 is about 863.7169202581.

The spelling of 644338798 in words is "six hundred forty-four million, three hundred thirty-eight thousand, seven hundred ninety-eight".