311320021 has 2 divisors, whose sum is σ = 311320022. Its totient is φ = 311320020.

The previous prime is 311320013. The next prime is 311320063. The reversal of 311320021 is 120023113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 179184996 + 132135025 = 13386^2 + 11495^2 .

It is a cyclic number.

It is not a de Polignac number, because 311320021 - 2³ = 311320013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 311319983 and 311320010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (311320081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 155660010 + 155660011.

It is an arithmetic number, because the mean of its divisors is an integer number (155660011).

Almost surely, 2^311320021 is an apocalyptic number.

It is an amenable number.

311320021 is a deficient number, since it is larger than the sum of its proper divisors (1).

311320021 is an equidigital number, since it uses as much as digits as its factorization.

311320021 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 311320021 is about 17644.2631186457. The cubic root of 311320021 is about 677.7492053101.

Adding to 311320021 its reverse (120023113), we get a palindrome (431343134).

The spelling of 311320021 in words is "three hundred eleven million, three hundred twenty thousand, twenty-one".