644377988 has 12 divisors (see below), whose sum is σ = 1128314880. Its totient is φ = 322002312.

The previous prime is 644377973. The next prime is 644378011. The reversal of 644377988 is 889773446.

It is an unprimeable number.

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, 38756 + ... + 52827.

It is an arithmetic number, because the mean of its divisors is an integer number (94026240).

Almost surely, 2^644377988 is an apocalyptic number.

It is an amenable number.

644377988 is a deficient number, since it is larger than the sum of its proper divisors (483936892).

644377988 is a wasteful number, since it uses less digits than its factorization.

644377988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93346 (or 93344 counting only the distinct ones).

The product of its digits is 8128512, while the sum is 56.

The square root of 644377988 is about 25384.6013953341. The cubic root of 644377988 is about 863.7344309114.

The spelling of 644377988 in words is "six hundred forty-four million, three hundred seventy-seven thousand, nine hundred eighty-eight".