644544445447 has 4 divisors (see below), whose sum is σ = 736622223376. Its totient is φ = 552466667520.

The previous prime is 644544445427. The next prime is 644544445463. The reversal of 644544445447 is 744544445446.

It is a happy number.

644544445447 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644544445447 - 2²⁷ = 644410227719 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644544445427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46038888954 + ... + 46038888967.

It is an arithmetic number, because the mean of its divisors is an integer number (184155555844).

Almost surely, 2^644544445447 is an apocalyptic number.

644544445447 is a deficient number, since it is larger than the sum of its proper divisors (92077777929).

644544445447 is an equidigital number, since it uses as much as digits as its factorization.

644544445447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92077777928.

The product of its digits is 68812800, while the sum is 55.

Subtracting 644544445447 from its reverse (744544445446), we obtain a palindrome (99999999999).

The spelling of 644544445447 in words is "six hundred forty-four billion, five hundred forty-four million, four hundred forty-five thousand, four hundred forty-seven".