311311981 has 2 divisors, whose sum is σ = 311311982. Its totient is φ = 311311980.

The previous prime is 311311961. The next prime is 311312039. The reversal of 311311981 is 189113113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 310957956 + 354025 = 17634^2 + 595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-311311981 is a prime.

It is a super-2 number, since 2×311311981² = 193830299028288722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (311311961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 155655990 + 155655991.

It is an arithmetic number, because the mean of its divisors is an integer number (155655991).

Almost surely, 2^311311981 is an apocalyptic number.

It is an amenable number.

311311981 is a deficient number, since it is larger than the sum of its proper divisors (1).

311311981 is an equidigital number, since it uses as much as digits as its factorization.

311311981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 28.

The square root of 311311981 is about 17644.0352810801. The cubic root of 311311981 is about 677.7433708523.

The spelling of 311311981 in words is "three hundred eleven million, three hundred eleven thousand, nine hundred eighty-one".