644000165641 has 4 divisors (see below), whose sum is σ = 736000189312. Its totient is φ = 552000141972.

The previous prime is 644000165617. The next prime is 644000165681. The reversal of 644000165641 is 146561000446.

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 644000165641 - 2⁹ = 644000165129 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644000165641.

It is not an unprimeable number, because it can be changed into a prime (644000165681) 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, 46000011825 + ... + 46000011838.

It is an arithmetic number, because the mean of its divisors is an integer number (184000047328).

Almost surely, 2^644000165641 is an apocalyptic number.

It is an amenable number.

644000165641 is a deficient number, since it is larger than the sum of its proper divisors (92000023671).

644000165641 is an equidigital number, since it uses as much as digits as its factorization.

644000165641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92000023670.

The product of its (nonzero) digits is 69120, while the sum is 37.

The spelling of 644000165641 in words is "six hundred forty-four billion, one hundred sixty-five thousand, six hundred forty-one".