81559843 has 2 divisors, whose sum is σ = 81559844. Its totient is φ = 81559842.

The previous prime is 81559813. The next prime is 81559847. The reversal of 81559843 is 34895518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81559843 - 2⁵ = 81559811 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81559843.

It is not a weakly prime, because it can be changed into another prime (81559847) 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, 40779921 + 40779922.

It is an arithmetic number, because the mean of its divisors is an integer number (40779922).

Almost surely, 2^81559843 is an apocalyptic number.

81559843 is a deficient number, since it is larger than the sum of its proper divisors (1).

81559843 is an equidigital number, since it uses as much as digits as its factorization.

81559843 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 172800, while the sum is 43.

The square root of 81559843 is about 9031.0488316696. The cubic root of 81559843 is about 433.6694145568.

The spelling of 81559843 in words is "eighty-one million, five hundred fifty-nine thousand, eight hundred forty-three".