81145 has 4 divisors (see below), whose sum is σ = 97380. Its totient is φ = 64912.

The previous prime is 81131. The next prime is 81157. The reversal of 81145 is 54118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54118 = 2 ⋅27059.

It can be written as a sum of positive squares in 2 ways, for example, as 59536 + 21609 = 244^2 + 147^2 .

It is a cyclic number.

It is not a de Polignac number, because 81145 - 2⁷ = 81017 is a prime.

It is a super-2 number, since 2×81145² = 13169022050, which contains 22 as substring.

81145 is a lucky number.

It is an unprimeable number.

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, 8110 + ... + 8119.

It is an arithmetic number, because the mean of its divisors is an integer number (24345).

2⁸¹¹⁴⁵ is an apocalyptic number.

It is an amenable number.

81145 is a deficient number, since it is larger than the sum of its proper divisors (16235).

81145 is a wasteful number, since it uses less digits than its factorization.

81145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16234.

The product of its digits is 160, while the sum is 19.

The square root of 81145 is about 284.8596145472. The cubic root of 81145 is about 43.2932897666.

The spelling of 81145 in words is "eighty-one thousand, one hundred forty-five".