664841361821 has 16 divisors (see below), whose sum is σ = 818286290304. Its totient is φ = 526015473984.

The previous prime is 664841361757. The next prime is 664841361827. The reversal of 664841361821 is 128163148466.

664841361821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 664841361821 - 2⁶ = 664841361757 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 664841361821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664841361827) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5720330 + ... + 5835396.

It is an arithmetic number, because the mean of its divisors is an integer number (51142893144).

Almost surely, 2^664841361821 is an apocalyptic number.

It is an amenable number.

664841361821 is a deficient number, since it is larger than the sum of its proper divisors (153444928483).

664841361821 is a wasteful number, since it uses less digits than its factorization.

664841361821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178580.

The product of its digits is 1327104, while the sum is 50.

The spelling of 664841361821 in words is "six hundred sixty-four billion, eight hundred forty-one million, three hundred sixty-one thousand, eight hundred twenty-one".