644127641 has 4 divisors (see below), whose sum is σ = 664905984. Its totient is φ = 623349300.

The previous prime is 644127629. The next prime is 644127697. The reversal of 644127641 is 146721446.

644127641 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644127641 - 2⁶ = 644127577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644127541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10389125 + ... + 10389186.

It is an arithmetic number, because the mean of its divisors is an integer number (166226496).

Almost surely, 2^644127641 is an apocalyptic number.

It is an amenable number.

644127641 is a deficient number, since it is larger than the sum of its proper divisors (20778343).

644127641 is a wasteful number, since it uses less digits than its factorization.

644127641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20778342.

The product of its digits is 32256, while the sum is 35.

The square root of 644127641 is about 25379.6698363080. The cubic root of 644127641 is about 863.6225600651.

The spelling of 644127641 in words is "six hundred forty-four million, one hundred twenty-seven thousand, six hundred forty-one".