81311 has 4 divisors (see below), whose sum is σ = 86112. Its totient is φ = 76512.

The previous prime is 81307. The next prime is 81331. The reversal of 81311 is 11318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11318 = 2 ⋅5659.

It is a cyclic number.

It is not a de Polignac number, because 81311 - 2² = 81307 is a prime.

It is a super-2 number, since 2×81311² = 13222957442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81331) 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, 2375 + ... + 2408.

It is an arithmetic number, because the mean of its divisors is an integer number (21528).

2⁸¹³¹¹ is an apocalyptic number.

81311 is a deficient number, since it is larger than the sum of its proper divisors (4801).

81311 is a wasteful number, since it uses less digits than its factorization.

81311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4800.

The product of its digits is 24, while the sum is 14.

The square root of 81311 is about 285.1508372774. The cubic root of 81311 is about 43.3227916501.

Adding to 81311 its reverse (11318), we get a palindrome (92629).

The spelling of 81311 in words is "eighty-one thousand, three hundred eleven".