644677671 has 8 divisors (see below), whose sum is σ = 937713024. Its totient is φ = 390713720.

The previous prime is 644677669. The next prime is 644677697. The reversal of 644677671 is 176776446.

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 644677671 - 2¹ = 644677669 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644677671.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644677471) 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, 9767811 + ... + 9767876.

It is an arithmetic number, because the mean of its divisors is an integer number (117214128).

Almost surely, 2^644677671 is an apocalyptic number.

644677671 is a deficient number, since it is larger than the sum of its proper divisors (293035353).

644677671 is a wasteful number, since it uses less digits than its factorization.

644677671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19535701.

The product of its digits is 1185408, while the sum is 48.

The square root of 644677671 is about 25390.5035594019. The cubic root of 644677671 is about 863.8683101009.

The spelling of 644677671 in words is "six hundred forty-four million, six hundred seventy-seven thousand, six hundred seventy-one".