81196729 has 4 divisors (see below), whose sum is σ = 81215476. Its totient is φ = 81177984.

The previous prime is 81196721. The next prime is 81196793. The reversal of 81196729 is 92769118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 41216400 + 39980329 = 6420^2 + 6323^2 .

It is a cyclic number.

It is not a de Polignac number, because 81196729 - 2³ = 81196721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81196721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 817 + ... + 12769.

It is an arithmetic number, because the mean of its divisors is an integer number (20303869).

Almost surely, 2^81196729 is an apocalyptic number.

It is an amenable number.

81196729 is a deficient number, since it is larger than the sum of its proper divisors (18747).

81196729 is a wasteful number, since it uses less digits than its factorization.

81196729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18746.

The product of its digits is 54432, while the sum is 43.

The square root of 81196729 is about 9010.9227607388. The cubic root of 81196729 is about 433.0248746971.

The spelling of 81196729 in words is "eighty-one million, one hundred ninety-six thousand, seven hundred twenty-nine".