311516921 has 2 divisors, whose sum is σ = 311516922. Its totient is φ = 311516920.

The previous prime is 311516917. The next prime is 311516941. The reversal of 311516921 is 129615113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 262796521 + 48720400 = 16211^2 + 6980^2 .

It is an emirp because it is prime and its reverse (129615113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 311516921 - 2² = 311516917 is a prime.

It is not a weakly prime, because it can be changed into another prime (311516941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 155758460 + 155758461.

It is an arithmetic number, because the mean of its divisors is an integer number (155758461).

Almost surely, 2^311516921 is an apocalyptic number.

It is an amenable number.

311516921 is a deficient number, since it is larger than the sum of its proper divisors (1).

311516921 is an equidigital number, since it uses as much as digits as its factorization.

311516921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 29.

The square root of 311516921 is about 17649.8419539666. The cubic root of 311516921 is about 677.8920601276.

The spelling of 311516921 in words is "three hundred eleven million, five hundred sixteen thousand, nine hundred twenty-one".