231221221 has 16 divisors (see below), whose sum is σ = 292584960. Its totient is φ = 177479280.

The previous prime is 231221209. The next prime is 231221239. The reversal of 231221221 is 122122132.

It is a happy number.

It is not a de Polignac number, because 231221221 - 2⁵ = 231221189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 231221195 and 231221204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231221201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17251 + ... + 27568.

It is an arithmetic number, because the mean of its divisors is an integer number (18286560).

Almost surely, 2^231221221 is an apocalyptic number.

It is an amenable number.

231221221 is a deficient number, since it is larger than the sum of its proper divisors (61363739).

231221221 is a wasteful number, since it uses less digits than its factorization.

231221221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44904.

The product of its digits is 96, while the sum is 16.

The square root of 231221221 is about 15205.9600486125. The cubic root of 231221221 is about 613.7750496037.

Adding to 231221221 its reverse (122122132), we get a palindrome (353343353).

The spelling of 231221221 in words is "two hundred thirty-one million, two hundred twenty-one thousand, two hundred twenty-one".