81505093 has 4 divisors (see below), whose sum is σ = 81638668. Its totient is φ = 81371520.

The previous prime is 81505091. The next prime is 81505129. The reversal of 81505093 is 39050518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12830724 + 68674369 = 3582^2 + 8287^2 .

It is a cyclic number.

It is not a de Polignac number, because 81505093 - 2¹ = 81505091 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 (81505091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65868 + ... + 67093.

It is an arithmetic number, because the mean of its divisors is an integer number (20409667).

Almost surely, 2^81505093 is an apocalyptic number.

It is an amenable number.

81505093 is a deficient number, since it is larger than the sum of its proper divisors (133575).

81505093 is a wasteful number, since it uses less digits than its factorization.

81505093 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133574.

The product of its (nonzero) digits is 5400, while the sum is 31.

The square root of 81505093 is about 9028.0171134087. The cubic root of 81505093 is about 433.5723540655.

The spelling of 81505093 in words is "eighty-one million, five hundred five thousand, ninety-three".