644612163 has 16 divisors (see below), whose sum is σ = 926392320. Its totient is φ = 396343584.

The previous prime is 644612161. The next prime is 644612173. The reversal of 644612163 is 361216446.

It is not a de Polignac number, because 644612163 - 2¹ = 644612161 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644612161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43420 + ... + 56342.

It is an arithmetic number, because the mean of its divisors is an integer number (57899520).

Almost surely, 2^644612163 is an apocalyptic number.

644612163 is a deficient number, since it is larger than the sum of its proper divisors (281780157).

644612163 is a wasteful number, since it uses less digits than its factorization.

644612163 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14218.

The product of its digits is 20736, while the sum is 33.

The square root of 644612163 is about 25389.2135167673. The cubic root of 644612163 is about 863.8390488619.

The spelling of 644612163 in words is "six hundred forty-four million, six hundred twelve thousand, one hundred sixty-three".