81247 has 4 divisors (see below), whose sum is σ = 82080. Its totient is φ = 80416.

The previous prime is 81239. The next prime is 81281. The reversal of 81247 is 74218.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 81247 - 2³ = 81239 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81047) 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, 247 + ... + 472.

It is an arithmetic number, because the mean of its divisors is an integer number (20520).

2⁸¹²⁴⁷ is an apocalyptic number.

81247 is a deficient number, since it is larger than the sum of its proper divisors (833).

81247 is a wasteful number, since it uses less digits than its factorization.

81247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832.

The product of its digits is 448, while the sum is 22.

The square root of 81247 is about 285.0385938781. The cubic root of 81247 is about 43.3114221903.

Subtracting from 81247 its sum of digits (22), we obtain a square (81225 = 285²).

The spelling of 81247 in words is "eighty-one thousand, two hundred forty-seven".