644404878 has 24 divisors (see below), whose sum is σ = 1503611928. Its totient is φ = 198278352.

The previous prime is 644404841. The next prime is 644404879. The reversal of 644404878 is 878404446.

644404878 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644404879) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1376700 + ... + 1377167.

It is an arithmetic number, because the mean of its divisors is an integer number (62650497).

Almost surely, 2^644404878 is an apocalyptic number.

644404878 is an abundant number, since it is smaller than the sum of its proper divisors (859207050).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644404878 is a wasteful number, since it uses less digits than its factorization.

644404878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2753888 (or 2753885 counting only the distinct ones).

The product of its (nonzero) digits is 688128, while the sum is 45.

The square root of 644404878 is about 25385.1310416157. The cubic root of 644404878 is about 863.7464453378.

The spelling of 644404878 in words is "six hundred forty-four million, four hundred four thousand, eight hundred seventy-eight".