82561 has 2 divisors, whose sum is σ = 82562. Its totient is φ = 82560.

The previous prime is 82559. The next prime is 82567. The reversal of 82561 is 16528.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78961 + 3600 = 281^2 + 60^2 .

It is a cyclic number.

It is not a de Polignac number, because 82561 - 2¹ = 82559 is a prime.

Together with 82559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (82567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41280 + 41281.

It is an arithmetic number, because the mean of its divisors is an integer number (41281).

2⁸²⁵⁶¹ is an apocalyptic number.

82561 is the 129-th centered decagonal number.

It is an amenable number.

82561 is a deficient number, since it is larger than the sum of its proper divisors (1).

82561 is an equidigital number, since it uses as much as digits as its factorization.

82561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 480, while the sum is 22.

The square root of 82561 is about 287.3343000757. The cubic root of 82561 is about 43.5436651428.

The spelling of 82561 in words is "eighty-two thousand, five hundred sixty-one".