81412909 has 2 divisors, whose sum is σ = 81412910. Its totient is φ = 81412908.

The previous prime is 81412907. The next prime is 81412927. The reversal of 81412909 is 90921418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52490025 + 28922884 = 7245^2 + 5378^2 .

It is a cyclic number.

It is not a de Polignac number, because 81412909 - 2¹ = 81412907 is a prime.

Together with 81412907, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81412901) 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, 40706454 + 40706455.

It is an arithmetic number, because the mean of its divisors is an integer number (40706455).

Almost surely, 2^81412909 is an apocalyptic number.

It is an amenable number.

81412909 is a deficient number, since it is larger than the sum of its proper divisors (1).

81412909 is an equidigital number, since it uses as much as digits as its factorization.

81412909 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 81412909 is about 9022.9102289671. The cubic root of 81412909 is about 433.4088325387.

The spelling of 81412909 in words is "eighty-one million, four hundred twelve thousand, nine hundred nine".