231321021 has 4 divisors (see below), whose sum is σ = 308428032. Its totient is φ = 154214012.

The previous prime is 231321019. The next prime is 231321043. The reversal of 231321021 is 120123132.

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 231321021 - 2¹ = 231321019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231321001) 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, 38553501 + ... + 38553506.

It is an arithmetic number, because the mean of its divisors is an integer number (77107008).

Almost surely, 2^231321021 is an apocalyptic number.

It is an amenable number.

231321021 is a deficient number, since it is larger than the sum of its proper divisors (77107011).

231321021 is an equidigital number, since it uses as much as digits as its factorization.

231321021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77107010.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 231321021 is about 15209.2413025765. The cubic root of 231321021 is about 613.8633430266.

Adding to 231321021 its reverse (120123132), we get a palindrome (351444153).

The spelling of 231321021 in words is "two hundred thirty-one million, three hundred twenty-one thousand, twenty-one".