81647 has 2 divisors, whose sum is σ = 81648. Its totient is φ = 81646.

The previous prime is 81637. The next prime is 81649. The reversal of 81647 is 74618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81647 - 2¹² = 77551 is a prime.

Together with 81649, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 9 and base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40823 + 40824.

It is an arithmetic number, because the mean of its divisors is an integer number (40824).

2⁸¹⁶⁴⁷ is an apocalyptic number.

81647 is a deficient number, since it is larger than the sum of its proper divisors (1).

81647 is an equidigital number, since it uses as much as digits as its factorization.

81647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1344, while the sum is 26.

The square root of 81647 is about 285.7393917541. The cubic root of 81647 is about 43.3823836423.

The spelling of 81647 in words is "eighty-one thousand, six hundred forty-seven".