81081001 has 2 divisors, whose sum is σ = 81081002. Its totient is φ = 81081000.

The previous prime is 81080977. The next prime is 81081019. The reversal of 81081001 is 10018018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60840000 + 20241001 = 7800^2 + 4499^2 .

It is a cyclic number.

It is not a de Polignac number, because 81081001 - 2¹¹ = 81078953 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81081001.

It is not a weakly prime, because it can be changed into another prime (81081031) 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, 40540500 + 40540501.

It is an arithmetic number, because the mean of its divisors is an integer number (40540501).

Almost surely, 2^81081001 is an apocalyptic number.

It is an amenable number.

81081001 is a deficient number, since it is larger than the sum of its proper divisors (1).

81081001 is an equidigital number, since it uses as much as digits as its factorization.

81081001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 19.

The square root of 81081001 is about 9004.4989310899. The cubic root of 81081001 is about 432.8190497803.

Adding to 81081001 its reverse (10018018), we get a palindrome (91099019).

The spelling of 81081001 in words is "eighty-one million, eighty-one thousand, one".