311681 has 2 divisors, whose sum is σ = 311682.
Its totient is φ = 311680.
The previous prime is 311677. The next prime is 311683. The reversal of 311681 is 186113.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 167281 + 144400 = 409^2 + 380^2
It is an emirp because it is prime and its reverse (186113) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 311681 - 22 = 311677 is a prime.
It is a super-2 number, since 2×3116812 = 194290091522, which contains 22 as substring.
Together with 311683, it forms a pair of twin primes.
It is a Chen prime.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 311681.
It is not a weakly prime, because it can be changed into another prime (311683) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 155840 + 155841.
It is an arithmetic number, because the mean of its divisors is an integer number (155841).
2311681 is an apocalyptic number.
It is an amenable number.
311681 is a deficient number, since it is larger than the sum of its proper divisors (1).
311681 is an equidigital number, since it uses as much as digits as its factorization.
311681 is an evil number, because the sum of its binary digits is even.
The product of its digits is 144, while the sum is 20.
The square root of 311681 is about 558.2839779180.
The cubic root of 311681 is about 67.8011056691.
Adding to 311681 its reverse (186113), we get a palindrome (497794).
The spelling of 311681 in words is "three hundred eleven thousand, six hundred eighty-one".