81071009 has 2 divisors, whose sum is σ = 81071010. Its totient is φ = 81071008.

The previous prime is 81070963. The next prime is 81071017. The reversal of 81071009 is 90017018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43824400 + 37246609 = 6620^2 + 6103^2 .

It is a cyclic number.

It is not a de Polignac number, because 81071009 - 2¹² = 81066913 is a prime.

It is not a weakly prime, because it can be changed into another prime (81071209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40535504 + 40535505.

It is an arithmetic number, because the mean of its divisors is an integer number (40535505).

Almost surely, 2^81071009 is an apocalyptic number.

It is an amenable number.

81071009 is a deficient number, since it is larger than the sum of its proper divisors (1).

81071009 is an equidigital number, since it uses as much as digits as its factorization.

81071009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 26.

The square root of 81071009 is about 9003.9440802351. The cubic root of 81071009 is about 432.8012695953.

The spelling of 81071009 in words is "eighty-one million, seventy-one thousand, nine".