81385543 has 2 divisors, whose sum is σ = 81385544. Its totient is φ = 81385542.

The previous prime is 81385481. The next prime is 81385559. The reversal of 81385543 is 34558318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81385543 - 2¹⁷ = 81254471 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81385573) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40692771 + 40692772.

It is an arithmetic number, because the mean of its divisors is an integer number (40692772).

Almost surely, 2^81385543 is an apocalyptic number.

81385543 is a deficient number, since it is larger than the sum of its proper divisors (1).

81385543 is an equidigital number, since it uses as much as digits as its factorization.

81385543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 57600, while the sum is 37.

The square root of 81385543 is about 9021.3936284811. The cubic root of 81385543 is about 433.3602653215.

The spelling of 81385543 in words is "eighty-one million, three hundred eighty-five thousand, five hundred forty-three".