81505103 has 4 divisors (see below), whose sum is σ = 81523200. Its totient is φ = 81487008.

The previous prime is 81505091. The next prime is 81505129. The reversal of 81505103 is 30150518.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 81505103 - 2¹⁰ = 81504079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81505133) 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 in 3 ways as a sum of consecutive naturals, for example, 3623 + ... + 13271.

It is an arithmetic number, because the mean of its divisors is an integer number (20380800).

Almost surely, 2^81505103 is an apocalyptic number.

81505103 is a deficient number, since it is larger than the sum of its proper divisors (18097).

81505103 is an equidigital number, since it uses as much as digits as its factorization.

81505103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18096.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 81505103 is about 9028.0176672401. The cubic root of 81505103 is about 433.5723717974.

The spelling of 81505103 in words is "eighty-one million, five hundred five thousand, one hundred three".