81729563 has 2 divisors, whose sum is σ = 81729564. Its totient is φ = 81729562.

The previous prime is 81729539. The next prime is 81729589. The reversal of 81729563 is 36592718.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81729563 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81729563.

It is not a weakly prime, because it can be changed into another prime (81729533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40864781 + 40864782.

It is an arithmetic number, because the mean of its divisors is an integer number (40864782).

Almost surely, 2^81729563 is an apocalyptic number.

81729563 is a deficient number, since it is larger than the sum of its proper divisors (1).

81729563 is an equidigital number, since it uses as much as digits as its factorization.

81729563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 41.

The square root of 81729563 is about 9040.4404206875. The cubic root of 81729563 is about 433.9700174662.

The spelling of 81729563 in words is "eighty-one million, seven hundred twenty-nine thousand, five hundred sixty-three".