231205221 has 12 divisors (see below), whose sum is σ = 359652748. Its totient is φ = 142280064.

The previous prime is 231205207. The next prime is 231205259. The reversal of 231205221 is 122502132.

231205221 is a `hidden beast` number, since 23 + 120 + 522 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 54022500 + 177182721 = 7350^2 + 13311^2 .

It is not a de Polignac number, because 231205221 - 2²¹ = 229108069 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 231205194 and 231205203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231205021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 987940 + ... + 988173.

Almost surely, 2^231205221 is an apocalyptic number.

It is an amenable number.

231205221 is a deficient number, since it is larger than the sum of its proper divisors (128447527).

231205221 is a wasteful number, since it uses less digits than its factorization.

231205221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1976132 (or 1976129 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 231205221 is about 15205.4339300133. The cubic root of 231205221 is about 613.7608919826.

Adding to 231205221 its reverse (122502132), we get a palindrome (353707353).

The spelling of 231205221 in words is "two hundred thirty-one million, two hundred five thousand, two hundred twenty-one".