311891 has 4 divisors (see below), whose sum is σ = 321984. Its totient is φ = 301800.

The previous prime is 311881. The next prime is 311897. The reversal of 311891 is 198113.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 198113 = 19 ⋅10427.

It is a cyclic number.

It is not a de Polignac number, because 311891 - 2⁶ = 311827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (311897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5000 + ... + 5061.

It is an arithmetic number, because the mean of its divisors is an integer number (80496).

2³¹¹⁸⁹¹ is an apocalyptic number.

311891 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

311891 is a deficient number, since it is larger than the sum of its proper divisors (10093).

311891 is a wasteful number, since it uses less digits than its factorization.

311891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10092.

The product of its digits is 216, while the sum is 23.

The square root of 311891 is about 558.4720225759. The cubic root of 311891 is about 67.8163296060.

The spelling of 311891 in words is "three hundred eleven thousand, eight hundred ninety-one".