81092009 has 2 divisors, whose sum is σ = 81092010. Its totient is φ = 81092008.

The previous prime is 81091993. The next prime is 81092017. The reversal of 81092009 is 90029018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69889600 + 11202409 = 8360^2 + 3347^2 .

It is a cyclic number.

It is not a de Polignac number, because 81092009 - 2⁴ = 81091993 is a prime.

It is not a weakly prime, because it can be changed into another prime (81092029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40546004 + 40546005.

It is an arithmetic number, because the mean of its divisors is an integer number (40546005).

Almost surely, 2^81092009 is an apocalyptic number.

It is an amenable number.

81092009 is a deficient number, since it is larger than the sum of its proper divisors (1).

81092009 is an equidigital number, since it uses as much as digits as its factorization.

81092009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 81092009 is about 9005.1101603478. The cubic root of 81092009 is about 432.8386361875.

The spelling of 81092009 in words is "eighty-one million, ninety-two thousand, nine".