644655042 has 24 divisors (see below), whose sum is σ = 1397288880. Its totient is φ = 214802520.

The previous prime is 644655019. The next prime is 644655073. The reversal of 644655042 is 240556446.

644655042 is a `hidden beast` number, since 64 + 4 + 6 + 550 + 42 = 666.

644655042 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 644654988 and 644655006.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57709 + ... + 67967.

It is an arithmetic number, because the mean of its divisors is an integer number (58220370).

Almost surely, 2^644655042 is an apocalyptic number.

644655042 is an abundant number, since it is smaller than the sum of its proper divisors (752633838).

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

644655042 is a wasteful number, since it uses less digits than its factorization.

644655042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13758 (or 13755 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 36.

The square root of 644655042 is about 25390.0579361293. The cubic root of 644655042 is about 863.8582023599.

The spelling of 644655042 in words is "six hundred forty-four million, six hundred fifty-five thousand, forty-two".