81245 has 4 divisors (see below), whose sum is σ = 97500. Its totient is φ = 64992.

The previous prime is 81239. The next prime is 81281. The reversal of 81245 is 54218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54218 = 2 ⋅27109.

It can be written as a sum of positive squares in 2 ways, for example, as 38809 + 42436 = 197^2 + 206^2 .

It is a cyclic number.

It is not a de Polignac number, because 81245 - 2⁶ = 81181 is a prime.

It is a congruent 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, 8120 + ... + 8129.

It is an arithmetic number, because the mean of its divisors is an integer number (24375).

2⁸¹²⁴⁵ is an apocalyptic number.

It is an amenable number.

81245 is a deficient number, since it is larger than the sum of its proper divisors (16255).

81245 is a wasteful number, since it uses less digits than its factorization.

81245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16254.

The product of its digits is 320, while the sum is 20.

The square root of 81245 is about 285.0350855597. The cubic root of 81245 is about 43.3110667985.

Subtracting from 81245 its sum of digits (20), we obtain a square (81225 = 285²).

The spelling of 81245 in words is "eighty-one thousand, two hundred forty-five".