644720686027446 has 64 divisors (see below), whose sum is σ = 1477932522992640. Its totient is φ = 183671026519680.

The previous prime is 644720686027409. The next prime is 644720686027471.

644720686027446 is nontrivially palindromic in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3993820 + ... + 36130208.

It is an arithmetic number, because the mean of its divisors is an integer number (23092695671760).

Almost surely, 2^{644720686027446} is an apocalyptic number.

644720686027446 is an abundant number, since it is smaller than the sum of its proper divisors (833211836965194).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644720686027446 is a wasteful number, since it uses less digits than its factorization.

644720686027446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32137789.

The product of its (nonzero) digits is 520224768, while the sum is 66.

The spelling of 644720686027446 in words is "six hundred forty-four trillion, seven hundred twenty billion, six hundred eighty-six million, twenty-seven thousand, four hundred forty-six".