644326078 has 24 divisors (see below), whose sum is σ = 1120031784. Its totient is φ = 275644800.

The previous prime is 644326057. The next prime is 644326087. The reversal of 644326078 is 870623446.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 644326078.

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 in 11 ways as a sum of consecutive naturals, for example, 44313 + ... + 57028.

It is an arithmetic number, because the mean of its divisors is an integer number (46667991).

Almost surely, 2^644326078 is an apocalyptic number.

644326078 is a deficient number, since it is larger than the sum of its proper divisors (475705706).

644326078 is a wasteful number, since it uses less digits than its factorization.

644326078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101388 (or 101371 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 40.

The square root of 644326078 is about 25383.5789044807. The cubic root of 644326078 is about 863.7112366273.

The spelling of 644326078 in words is "six hundred forty-four million, three hundred twenty-six thousand, seventy-eight".