813881 has 4 divisors (see below), whose sum is σ = 818292. Its totient is φ = 809472.

The previous prime is 813871. The next prime is 813893. The reversal of 813881 is 188318.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 477481 + 336400 = 691^2 + 580^2 .

It is a cyclic number.

It is not a de Polignac number, because 813881 - 2⁶ = 813817 is a prime.

It is a super-2 number, since 2×813881² = 1324804564322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 813881.

It is not an unprimeable number, because it can be changed into a prime (813811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1916 + ... + 2301.

It is an arithmetic number, because the mean of its divisors is an integer number (204573).

2⁸¹³⁸⁸¹ is an apocalyptic number.

It is an amenable number.

813881 is a deficient number, since it is larger than the sum of its proper divisors (4411).

813881 is a wasteful number, since it uses less digits than its factorization.

813881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4410.

The product of its digits is 1536, while the sum is 29.

The square root of 813881 is about 902.1535346048. The cubic root of 813881 is about 93.3656166666.

The spelling of 813881 in words is "eight hundred thirteen thousand, eight hundred eighty-one".