81331589 has 2 divisors, whose sum is σ = 81331590. Its totient is φ = 81331588.

The previous prime is 81331561. The next prime is 81331633. The reversal of 81331589 is 98513318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78180964 + 3150625 = 8842^2 + 1775^2 .

It is a cyclic number.

It is not a de Polignac number, because 81331589 - 2⁸ = 81331333 is a prime.

It is a super-2 number, since 2×81331589² = 13229654738529842, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81331489) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40665794 + 40665795.

It is an arithmetic number, because the mean of its divisors is an integer number (40665795).

Almost surely, 2^81331589 is an apocalyptic number.

It is an amenable number.

81331589 is a deficient number, since it is larger than the sum of its proper divisors (1).

81331589 is an equidigital number, since it uses as much as digits as its factorization.

81331589 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 38.

The square root of 81331589 is about 9018.4027965045. The cubic root of 81331589 is about 433.2644797243.

The spelling of 81331589 in words is "eighty-one million, three hundred thirty-one thousand, five hundred eighty-nine".