81429109 has 2 divisors, whose sum is σ = 81429110. Its totient is φ = 81429108.

The previous prime is 81429107. The next prime is 81429113. The reversal of 81429109 is 90192418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 68310225 + 13118884 = 8265^2 + 3622^2 .

It is a cyclic number.

It is not a de Polignac number, because 81429109 - 2¹ = 81429107 is a prime.

Together with 81429107, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81429107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40714554 + 40714555.

It is an arithmetic number, because the mean of its divisors is an integer number (40714555).

Almost surely, 2^81429109 is an apocalyptic number.

It is an amenable number.

81429109 is a deficient number, since it is larger than the sum of its proper divisors (1).

81429109 is an equidigital number, since it uses as much as digits as its factorization.

81429109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 81429109 is about 9023.8078991078. The cubic root of 81429109 is about 433.4375780105.

The spelling of 81429109 in words is "eighty-one million, four hundred twenty-nine thousand, one hundred nine".