205310340221 has 4 divisors (see below), whose sum is σ = 234640388832. Its totient is φ = 175980291612.

The previous prime is 205310340211. The next prime is 205310340269. The reversal of 205310340221 is 122043013502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122043013502 = 2 ⋅61021506751.

It is a cyclic number.

It is not a de Polignac number, because 205310340221 - 2¹⁰ = 205310339197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205310340211) 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, 14665024295 + ... + 14665024308.

It is an arithmetic number, because the mean of its divisors is an integer number (58660097208).

Almost surely, 2^205310340221 is an apocalyptic number.

It is an amenable number.

205310340221 is a deficient number, since it is larger than the sum of its proper divisors (29330048611).

205310340221 is an equidigital number, since it uses as much as digits as its factorization.

205310340221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29330048610.

The product of its (nonzero) digits is 1440, while the sum is 23.

Adding to 205310340221 its reverse (122043013502), we get a palindrome (327353353723).

The spelling of 205310340221 in words is "two hundred five billion, three hundred ten million, three hundred forty thousand, two hundred twenty-one".