243121210205 has 4 divisors (see below), whose sum is σ = 291745452252. Its totient is φ = 194496968160.

The previous prime is 243121210183. The next prime is 243121210217. The reversal of 243121210205 is 502012121342.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 502012121342 = 2 ⋅251006060671.

It can be written as a sum of positive squares in 2 ways, for example, as 145150332196 + 97970878009 = 380986^2 + 313003^2 .

It is not a de Polignac number, because 243121210205 - 2¹² = 243121206109 is a prime.

It is a super-2 number, since 2×243121210205² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24312121016 + ... + 24312121025.

It is an arithmetic number, because the mean of its divisors is an integer number (72936363063).

Almost surely, 2^243121210205 is an apocalyptic number.

It is an amenable number.

243121210205 is a deficient number, since it is larger than the sum of its proper divisors (48624242047).

243121210205 is an equidigital number, since it uses as much as digits as its factorization.

243121210205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48624242046.

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 243121210205 its reverse (502012121342), we get a palindrome (745133331547).

The spelling of 243121210205 in words is "two hundred forty-three billion, one hundred twenty-one million, two hundred ten thousand, two hundred five".