81211 has 4 divisors (see below), whose sum is σ = 87472. Its totient is φ = 74952.

The previous prime is 81203. The next prime is 81223. The reversal of 81211 is 11218.

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

It is a cyclic number.

It is not a de Polignac number, because 81211 - 2³ = 81203 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 6247 = 81211 / (8 + 1 + 2 + 1 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81191 and 81200.

It is not an unprimeable number, because it can be changed into a prime (81281) 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, 3111 + ... + 3136.

It is an arithmetic number, because the mean of its divisors is an integer number (21868).

2⁸¹²¹¹ is an apocalyptic number.

81211 is a deficient number, since it is larger than the sum of its proper divisors (6261).

81211 is a wasteful number, since it uses less digits than its factorization.

81211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6260.

The product of its digits is 16, while the sum is 13.

The square root of 81211 is about 284.9754375380. The cubic root of 81211 is about 43.3050242451.

Adding to 81211 its reverse (11218), we get a palindrome (92429).

It can be divided in two parts, 81 and 211, that added together give a palindrome (292).

The spelling of 81211 in words is "eighty-one thousand, two hundred eleven".