644512716 has 36 divisors (see below), whose sum is σ = 1700021232. Its totient is φ = 205496544.

The previous prime is 644512703. The next prime is 644512741. The reversal of 644512716 is 617215446.

644512716 is a `hidden beast` number, since 644 + 5 + 1 + 2 + 7 + 1 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 388371 + ... + 390026.

It is an arithmetic number, because the mean of its divisors is an integer number (47222812).

Almost surely, 2^644512716 is an apocalyptic number.

It is an amenable number.

644512716 is an abundant number, since it is smaller than the sum of its proper divisors (1055508516).

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

644512716 is a wasteful number, since it uses less digits than its factorization.

644512716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778430 (or 778425 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 644512716 is about 25387.2549914322. The cubic root of 644512716 is about 863.7946238961.

The spelling of 644512716 in words is "six hundred forty-four million, five hundred twelve thousand, seven hundred sixteen".