644375671 has 8 divisors (see below), whose sum is σ = 681336320. Its totient is φ = 607719672.

The previous prime is 644375663. The next prime is 644375707. The reversal of 644375671 is 176573446.

644375671 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644375671 - 2³ = 644375663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644375371) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71805 + ... + 80278.

It is an arithmetic number, because the mean of its divisors is an integer number (85167040).

Almost surely, 2^644375671 is an apocalyptic number.

644375671 is a deficient number, since it is larger than the sum of its proper divisors (36960649).

644375671 is a wasteful number, since it uses less digits than its factorization.

644375671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152325.

The product of its digits is 423360, while the sum is 43.

The square root of 644375671 is about 25384.5557573892. Note that the first 3 decimals coincide. The cubic root of 644375671 is about 863.7333956624.

The spelling of 644375671 in words is "six hundred forty-four million, three hundred seventy-five thousand, six hundred seventy-one".