81563 has 2 divisors, whose sum is σ = 81564. Its totient is φ = 81562.

The previous prime is 81559. The next prime is 81569. The reversal of 81563 is 36518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81563 - 2² = 81559 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81569) by changing a digit.

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 as a sum of consecutive naturals, namely, 40781 + 40782.

It is an arithmetic number, because the mean of its divisors is an integer number (40782).

2⁸¹⁵⁶³ is an apocalyptic number.

81563 is a deficient number, since it is larger than the sum of its proper divisors (1).

81563 is an equidigital number, since it uses as much as digits as its factorization.

81563 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 23.

The square root of 81563 is about 285.5923668448. The cubic root of 81563 is about 43.3675009944.

It can be divided in two parts, 815 and 63, that added together give a palindrome (878).

The spelling of 81563 in words is "eighty-one thousand, five hundred sixty-three".