1644064671881 has 8 divisors (see below), whose sum is σ = 1648560682560. Its totient is φ = 1639574726832.

The previous prime is 1644064671793. The next prime is 1644064671901. The reversal of 1644064671881 is 1881764604461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1644064671881 is a prime.

It is a super-3 number, since 3×1644064671881³ (a number of 38 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1644064671181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 973310 + ... + 2058023.

It is an arithmetic number, because the mean of its divisors is an integer number (206070085320).

Almost surely, 2^{1644064671881} is an apocalyptic number.

It is an amenable number.

1644064671881 is a deficient number, since it is larger than the sum of its proper divisors (4496010679).

1644064671881 is an equidigital number, since it uses as much as digits as its factorization.

1644064671881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3032815.

The product of its (nonzero) digits is 6193152, while the sum is 56.

The spelling of 1644064671881 in words is "one trillion, six hundred forty-four billion, sixty-four million, six hundred seventy-one thousand, eight hundred eighty-one".