664838811121 has 4 divisors (see below), whose sum is σ = 664920284644. Its totient is φ = 664757337600.

The previous prime is 664838811079. The next prime is 664838811149. The reversal of 664838811121 is 121118838466.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 187109018721 + 477729792400 = 432561^2 + 691180^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664838811121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664838811821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40724520 + ... + 40740841.

It is an arithmetic number, because the mean of its divisors is an integer number (166230071161).

Almost surely, 2^664838811121 is an apocalyptic number.

It is an amenable number.

664838811121 is a deficient number, since it is larger than the sum of its proper divisors (81473523).

664838811121 is an equidigital number, since it uses as much as digits as its factorization.

664838811121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81473522.

The product of its digits is 442368, while the sum is 49.

The spelling of 664838811121 in words is "six hundred sixty-four billion, eight hundred thirty-eight million, eight hundred eleven thousand, one hundred twenty-one".