81941729 has 2 divisors, whose sum is σ = 81941730. Its totient is φ = 81941728.

The previous prime is 81941681. The next prime is 81941747. The reversal of 81941729 is 92714918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81938704 + 3025 = 9052^2 + 55^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81941729 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81941749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40970864 + 40970865.

It is an arithmetic number, because the mean of its divisors is an integer number (40970865).

Almost surely, 2^81941729 is an apocalyptic number.

It is an amenable number.

81941729 is a deficient number, since it is larger than the sum of its proper divisors (1).

81941729 is an equidigital number, since it uses as much as digits as its factorization.

81941729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 41.

The square root of 81941729 is about 9052.1670886037. The cubic root of 81941729 is about 434.3452147270.

The spelling of 81941729 in words is "eighty-one million, nine hundred forty-one thousand, seven hundred twenty-nine".