644855646558446 has 16 divisors (see below), whose sum is σ = 967471134570720. Its totient is φ = 322365269358240.

The previous prime is 644855646558433. The next prime is 644855646558449.

644855646558446 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×644855646558446² (a number of 30 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644855646558449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2591332895 + ... + 2591581733.

It is an arithmetic number, because the mean of its divisors is an integer number (60466945910670).

Almost surely, 2^{644855646558446} is an apocalyptic number.

644855646558446 is a deficient number, since it is larger than the sum of its proper divisors (322615488012274).

644855646558446 is a wasteful number, since it uses less digits than its factorization.

644855646558446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495019.

The product of its digits is 53084160000, while the sum is 80.

The spelling of 644855646558446 in words is "six hundred forty-four trillion, eight hundred fifty-five billion, six hundred forty-six million, five hundred fifty-eight thousand, four hundred forty-six".