231320221 has 4 divisors (see below), whose sum is σ = 252349344. Its totient is φ = 210291100.

The previous prime is 231320191. The next prime is 231320227. The reversal of 231320221 is 122023132.

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.

It is a cyclic number.

It is not a de Polignac number, because 231320221 - 2⁹ = 231319709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 231320195 and 231320204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231320227) 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, 10514545 + ... + 10514566.

It is an arithmetic number, because the mean of its divisors is an integer number (63087336).

Almost surely, 2^231320221 is an apocalyptic number.

It is an amenable number.

231320221 is a deficient number, since it is larger than the sum of its proper divisors (21029123).

231320221 is a wasteful number, since it uses less digits than its factorization.

231320221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21029122.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 231320221 is about 15209.2150027541. The cubic root of 231320221 is about 613.8626353647.

Adding to 231320221 its reverse (122023132), we get a palindrome (353343353).

The spelling of 231320221 in words is "two hundred thirty-one million, three hundred twenty thousand, two hundred twenty-one".