644163105 has 24 divisors (see below), whose sum is σ = 1065004416. Its totient is φ = 332463840.

The previous prime is 644163101. The next prime is 644163119. The reversal of 644163105 is 501361446.

It is not a de Polignac number, because 644163105 - 2² = 644163101 is a prime.

It is a super-2 number, since 2×644163105² = 829892211686482050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644163101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7929 + ... + 36758.

It is an arithmetic number, because the mean of its divisors is an integer number (44375184).

Almost surely, 2^644163105 is an apocalyptic number.

It is an amenable number.

644163105 is a deficient number, since it is larger than the sum of its proper divisors (420841311).

644163105 is a wasteful number, since it uses less digits than its factorization.

644163105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44757 (or 44726 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 644163105 is about 25380.3684961428. The cubic root of 644163105 is about 863.6384093815.

The spelling of 644163105 in words is "six hundred forty-four million, one hundred sixty-three thousand, one hundred five".