231328561161821 has 4 divisors (see below), whose sum is σ = 234497445561372. Its totient is φ = 228159676762272.

The previous prime is 231328561161809. The next prime is 231328561161823. The reversal of 231328561161821 is 128161165823132.

231328561161821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 69195961564921 + 162132599596900 = 8318411^2 + 12733130^2 .

It is a cyclic number.

It is not a de Polignac number, because 231328561161821 - 2¹⁸ = 231328560899677 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 231328561161821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231328561161823) 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, 1584442199666 + ... + 1584442199811.

It is an arithmetic number, because the mean of its divisors is an integer number (58624361390343).

Almost surely, 2^{231328561161821} is an apocalyptic number.

It is an amenable number.

231328561161821 is a deficient number, since it is larger than the sum of its proper divisors (3168884399551).

231328561161821 is an equidigital number, since it uses as much as digits as its factorization.

231328561161821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3168884399550.

The product of its digits is 829440, while the sum is 50.

The spelling of 231328561161821 in words is "two hundred thirty-one trillion, three hundred twenty-eight billion, five hundred sixty-one million, one hundred sixty-one thousand, eight hundred twenty-one".