644577647 has 8 divisors (see below), whose sum is σ = 738749856. Its totient is φ = 550927872.

The previous prime is 644577643. The next prime is 644577649. The reversal of 644577647 is 746775446.

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 644577647 - 2² = 644577643 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644577595 and 644577604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644577643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127958 + ... + 132899.

It is an arithmetic number, because the mean of its divisors is an integer number (92343732).

Almost surely, 2^644577647 is an apocalyptic number.

644577647 is a deficient number, since it is larger than the sum of its proper divisors (94172209).

644577647 is a wasteful number, since it uses less digits than its factorization.

644577647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261217.

The product of its digits is 3951360, while the sum is 50.

The square root of 644577647 is about 25388.5337701885. The cubic root of 644577647 is about 863.8236303915.

The spelling of 644577647 in words is "six hundred forty-four million, five hundred seventy-seven thousand, six hundred forty-seven".