311813 has 4 divisors (see below), whose sum is σ = 315840. Its totient is φ = 307788.

The previous prime is 311807. The next prime is 311821. The reversal of 311813 is 318113.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 318113 = 23 ⋅13831.

It is a cyclic number.

It is not a de Polignac number, because 311813 - 2⁶ = 311749 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 311791 and 311800.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 311813.

It is not an unprimeable number, because it can be changed into a prime (311803) 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, 1895 + ... + 2052.

It is an arithmetic number, because the mean of its divisors is an integer number (78960).

2³¹¹⁸¹³ is an apocalyptic number.

It is an amenable number.

311813 is a deficient number, since it is larger than the sum of its proper divisors (4027).

311813 is an equidigital number, since it uses as much as digits as its factorization.

311813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4026.

The product of its digits is 72, while the sum is 17.

The square root of 311813 is about 558.4021848095. The cubic root of 311813 is about 67.8106757988.

Adding to 311813 its reverse (318113), we get a palindrome (629926).

The spelling of 311813 in words is "three hundred eleven thousand, eight hundred thirteen".