644144441445 has 16 divisors (see below), whose sum is σ = 1145145673920. Its totient is φ = 343543702032.

The previous prime is 644144441443. The next prime is 644144441491. The reversal of 644144441445 is 544144441446.

644144441445 is a `hidden beast` number, since 64 + 4 + 1 + 4 + 444 + 144 + 5 = 666.

It is not a de Polignac number, because 644144441445 - 2¹ = 644144441443 is a prime.

It is a super-2 number, since 2×644144441445² (a number of 24 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 644144441445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644144441443) 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, 2385720019 + ... + 2385720288.

It is an arithmetic number, because the mean of its divisors is an integer number (71571604620).

Almost surely, 2^644144441445 is an apocalyptic number.

It is an amenable number.

644144441445 is a deficient number, since it is larger than the sum of its proper divisors (501001232475).

644144441445 is a wasteful number, since it uses less digits than its factorization.

644144441445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4771440321 (or 4771440315 counting only the distinct ones).

The product of its digits is 1966080, while the sum is 45.

Subtracting from 644144441445 its reverse (544144441446), we obtain a palindrome (99999999999).

The spelling of 644144441445 in words is "six hundred forty-four billion, one hundred forty-four million, four hundred forty-one thousand, four hundred forty-five".