644032401515121 has 24 divisors (see below), whose sum is σ = 928622431558080. Its totient is φ = 396525696456736.

The previous prime is 644032401515117. The next prime is 644032401515141. The reversal of 644032401515121 is 121515104230446.

It is not a de Polignac number, because 644032401515121 - 2² = 644032401515117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644032401515121.

It is not an unprimeable number, because it can be changed into a prime (644032401515141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6996807741 + ... + 6996899786.

It is an arithmetic number, because the mean of its divisors is an integer number (38692601314920).

Almost surely, 2^{644032401515121} is an apocalyptic number.

It is an amenable number.

644032401515121 is a deficient number, since it is larger than the sum of its proper divisors (284590030042959).

644032401515121 is a wasteful number, since it uses less digits than its factorization.

644032401515121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13993707605 (or 13993707582 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 39.

Adding to 644032401515121 its reverse (121515104230446), we get a palindrome (765547505745567).

The spelling of 644032401515121 in words is "six hundred forty-four trillion, thirty-two billion, four hundred one million, five hundred fifteen thousand, one hundred twenty-one".