644643105 has 32 divisors (see below), whose sum is σ = 1044845568. Its totient is φ = 339360000.

The previous prime is 644643053. The next prime is 644643107. The reversal of 644643105 is 501346446.

It is not a de Polignac number, because 644643105 - 2¹⁶ = 644577569 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644643107) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 919255 + ... + 919955.

It is an arithmetic number, because the mean of its divisors is an integer number (32651424).

Almost surely, 2^644643105 is an apocalyptic number.

It is an amenable number.

644643105 is a deficient number, since it is larger than the sum of its proper divisors (400202463).

644643105 is a wasteful number, since it uses less digits than its factorization.

644643105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1417.

The product of its (nonzero) digits is 34560, while the sum is 33.

The square root of 644643105 is about 25389.8228627141. The cubic root of 644643105 is about 863.8528703408.

The spelling of 644643105 in words is "six hundred forty-four million, six hundred forty-three thousand, one hundred five".