81121 has 4 divisors (see below), whose sum is σ = 84672. Its totient is φ = 77572.

The previous prime is 81119. The next prime is 81131. The reversal of 81121 is 12118.

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.

It is a cyclic number.

It is not a de Polignac number, because 81121 - 2¹ = 81119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81101) 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, 1741 + ... + 1786.

It is an arithmetic number, because the mean of its divisors is an integer number (21168).

2⁸¹¹²¹ is an apocalyptic number.

It is an amenable number.

81121 is a deficient number, since it is larger than the sum of its proper divisors (3551).

81121 is a wasteful number, since it uses less digits than its factorization.

81121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3550.

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

The square root of 81121 is about 284.8174854183. The cubic root of 81121 is about 43.2890211059.

Adding to 81121 its reverse (12118), we get a palindrome (93239).

It can be divided in two parts, 81 and 121, that multiplied together give a square (9801 = 99²).

The spelling of 81121 in words is "eighty-one thousand, one hundred twenty-one".