644625563 has 16 divisors (see below), whose sum is σ = 682905600. Its totient is φ = 607635840.

The previous prime is 644625547. The next prime is 644625649. The reversal of 644625563 is 365526446.

It is a happy number.

644625563 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 644625563 - 2⁴ = 644625547 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 644625563.

It is not an unprimeable number, because it can be changed into a prime (644625503) 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, 205118 + ... + 208236.

It is an arithmetic number, because the mean of its divisors is an integer number (42681600).

Almost surely, 2^644625563 is an apocalyptic number.

644625563 is a deficient number, since it is larger than the sum of its proper divisors (38280037).

644625563 is a wasteful number, since it uses less digits than its factorization.

644625563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3322.

The product of its digits is 518400, while the sum is 41.

The square root of 644625563 is about 25389.4774069889. The cubic root of 644625563 is about 863.8450345609.

The spelling of 644625563 in words is "six hundred forty-four million, six hundred twenty-five thousand, five hundred sixty-three".