81105559 has 2 divisors, whose sum is σ = 81105560. Its totient is φ = 81105558.

The previous prime is 81105523. The next prime is 81105569. The reversal of 81105559 is 95550118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81105559 - 2²¹ = 79008407 is a prime.

It is a super-2 number, since 2×81105559² = 13156223401404962, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81105569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40552779 + 40552780.

It is an arithmetic number, because the mean of its divisors is an integer number (40552780).

Almost surely, 2^81105559 is an apocalyptic number.

81105559 is a deficient number, since it is larger than the sum of its proper divisors (1).

81105559 is an equidigital number, since it uses as much as digits as its factorization.

81105559 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9000, while the sum is 34.

The square root of 81105559 is about 9005.8624795185. The cubic root of 81105559 is about 432.8627431123.

The spelling of 81105559 in words is "eighty-one million, one hundred five thousand, five hundred fifty-nine".