644653071 has 12 divisors (see below), whose sum is σ = 980174520. Its totient is φ = 407149200.

The previous prime is 644653067. The next prime is 644653133. The reversal of 644653071 is 170356446.

It is a happy number.

644653071 is a `hidden beast` number, since 644 + 6 + 5 + 3 + 0 + 7 + 1 = 666.

It is not a de Polignac number, because 644653071 - 2² = 644653067 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644653171) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 1884780 + ... + 1885121.

It is an arithmetic number, because the mean of its divisors is an integer number (81681210).

Almost surely, 2^644653071 is an apocalyptic number.

644653071 is a deficient number, since it is larger than the sum of its proper divisors (335521449).

644653071 is a wasteful number, since it uses less digits than its factorization.

644653071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3769926 (or 3769923 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The square root of 644653071 is about 25390.0191216943. The cubic root of 644653071 is about 863.8573219582.

The spelling of 644653071 in words is "six hundred forty-four million, six hundred fifty-three thousand, seventy-one".