81811589 has 2 divisors, whose sum is σ = 81811590. Its totient is φ = 81811588.

The previous prime is 81811577. The next prime is 81811651. The reversal of 81811589 is 98511818.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43890625 + 37920964 = 6625^2 + 6158^2 .

It is a cyclic number.

It is not a de Polignac number, because 81811589 - 2⁸ = 81811333 is a prime.

It is a Chen prime.

It is a congruent number.

It is a weakly prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40905794 + 40905795.

It is an arithmetic number, because the mean of its divisors is an integer number (40905795).

Almost surely, 2^81811589 is an apocalyptic number.

It is an amenable number.

81811589 is a deficient number, since it is larger than the sum of its proper divisors (1).

81811589 is an equidigital number, since it uses as much as digits as its factorization.

81811589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23040, while the sum is 41.

The square root of 81811589 is about 9044.9758982542. The cubic root of 81811589 is about 434.1151502731.

The spelling of 81811589 in words is "eighty-one million, eight hundred eleven thousand, five hundred eighty-nine".