644544445445 has 8 divisors (see below), whose sum is σ = 784048586136. Its totient is φ = 508572055296.

The previous prime is 644544445427. The next prime is 644544445463. The reversal of 644544445445 is 544544445446.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (644544445427) and next prime (644544445463).

It can be written as a sum of positive squares in 4 ways, for example, as 264474661441 + 380069784004 = 514271^2 + 616498^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644544445445 - 2⁸ = 644544445189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 882937232 + ... + 882937961.

It is an arithmetic number, because the mean of its divisors is an integer number (98006073267).

Almost surely, 2^644544445445 is an apocalyptic number.

It is an amenable number.

644544445445 is a deficient number, since it is larger than the sum of its proper divisors (139504140691).

644544445445 is a wasteful number, since it uses less digits than its factorization.

644544445445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1765875271.

The product of its digits is 49152000, while the sum is 53.

Subtracting from 644544445445 its reverse (544544445446), we obtain a palindrome (99999999999).

The spelling of 644544445445 in words is "six hundred forty-four billion, five hundred forty-four million, four hundred forty-five thousand, four hundred forty-five".