81440159 has 2 divisors, whose sum is σ = 81440160. Its totient is φ = 81440158.

The previous prime is 81440129. The next prime is 81440173. The reversal of 81440159 is 95104418.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81440159 - 2⁸ = 81439903 is a prime.

It is equal to p_4748720 and since 81440159 and 4748720 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81440129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40720079 + 40720080.

It is an arithmetic number, because the mean of its divisors is an integer number (40720080).

Almost surely, 2^81440159 is an apocalyptic number.

81440159 is a deficient number, since it is larger than the sum of its proper divisors (1).

81440159 is an equidigital number, since it uses as much as digits as its factorization.

81440159 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 81440159 is about 9024.4201475774. The cubic root of 81440159 is about 433.4571830742.

The spelling of 81440159 in words is "eighty-one million, four hundred forty thousand, one hundred fifty-nine".