81018689 has 2 divisors, whose sum is σ = 81018690. Its totient is φ = 81018688.

The previous prime is 81018683. The next prime is 81018697. The reversal of 81018689 is 98681018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73273600 + 7745089 = 8560^2 + 2783^2 .

It is a cyclic number.

It is not a de Polignac number, because 81018689 - 2⁸ = 81018433 is a prime.

It is not a weakly prime, because it can be changed into another prime (81018683) 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, 40509344 + 40509345.

It is an arithmetic number, because the mean of its divisors is an integer number (40509345).

Almost surely, 2^81018689 is an apocalyptic number.

It is an amenable number.

81018689 is a deficient number, since it is larger than the sum of its proper divisors (1).

81018689 is an equidigital number, since it uses as much as digits as its factorization.

81018689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27648, while the sum is 41.

The square root of 81018689 is about 9001.0382178946. The cubic root of 81018689 is about 432.7081453261.

The spelling of 81018689 in words is "eighty-one million, eighteen thousand, six hundred eighty-nine".