231210221 has 16 divisors (see below), whose sum is σ = 270527040. Its totient is φ = 195361920.

The previous prime is 231210197. The next prime is 231210223. The reversal of 231210221 is 122012132.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 231210221 - 2⁶ = 231210157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 231210196 and 231210205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231210223) 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, 641 + ... + 21513.

It is an arithmetic number, because the mean of its divisors is an integer number (16907940).

Almost surely, 2^231210221 is an apocalyptic number.

It is an amenable number.

231210221 is a deficient number, since it is larger than the sum of its proper divisors (39316819).

231210221 is a wasteful number, since it uses less digits than its factorization.

231210221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20956.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 231210221 is about 15205.5983440311. The cubic root of 231210221 is about 613.7653163094.

Adding to 231210221 its reverse (122012132), we get a palindrome (353222353).

The spelling of 231210221 in words is "two hundred thirty-one million, two hundred ten thousand, two hundred twenty-one".