644346666643446 has 24 divisors (see below), whose sum is σ = 1503475555501920. Its totient is φ = 198260512813296.

The previous prime is 644346666643429. The next prime is 644346666643469.

644346666643446 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×644346666643446² (a number of 30 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1376809116526 + ... + 1376809116993.

It is an arithmetic number, because the mean of its divisors is an integer number (62644814812580).

Almost surely, 2^{644346666643446} is an apocalyptic number.

644346666643446 is an abundant number, since it is smaller than the sum of its proper divisors (859128888858474).

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

644346666643446 is a wasteful number, since it uses less digits than its factorization.

644346666643446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2753618233540 (or 2753618233537 counting only the distinct ones).

The product of its digits is 10319560704, while the sum is 72.

The spelling of 644346666643446 in words is "six hundred forty-four trillion, three hundred forty-six billion, six hundred sixty-six million, six hundred forty-three thousand, four hundred forty-six".