321310021 has 2 divisors, whose sum is σ = 321310022. Its totient is φ = 321310020.

The previous prime is 321310019. The next prime is 321310027. The reversal of 321310021 is 120013123.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 305865121 + 15444900 = 17489^2 + 3930^2 .

It is a cyclic number.

It is not a de Polignac number, because 321310021 - 2¹ = 321310019 is a prime.

Together with 321310019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 321309983 and 321310010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (321310027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160655010 + 160655011.

It is an arithmetic number, because the mean of its divisors is an integer number (160655011).

Almost surely, 2^321310021 is an apocalyptic number.

It is an amenable number.

321310021 is a deficient number, since it is larger than the sum of its proper divisors (1).

321310021 is an equidigital number, since it uses as much as digits as its factorization.

321310021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 321310021 is about 17925.1226216168. The cubic root of 321310021 is about 684.9224847019.

Adding to 321310021 its reverse (120013123), we get a palindrome (441323144).

The spelling of 321310021 in words is "three hundred twenty-one million, three hundred ten thousand, twenty-one".