81586585081 has 4 divisors (see below), whose sum is σ = 81599102964. Its totient is φ = 81574067200.

The previous prime is 81586585033. The next prime is 81586585121. The reversal of 81586585081 is 18058568518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18058568518 = 2 ⋅9029284259.

It can be written as a sum of positive squares in 2 ways, for example, as 70235600400 + 11350984681 = 265020^2 + 106541^2 .

It is a cyclic number.

It is not a de Polignac number, because 81586585081 - 2¹¹ = 81586583033 is a prime.

It is a super-2 number, since 2×81586585081² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81586585681) 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, 6249160 + ... + 6262201.

It is an arithmetic number, because the mean of its divisors is an integer number (20399775741).

Almost surely, 2^81586585081 is an apocalyptic number.

It is an amenable number.

81586585081 is a deficient number, since it is larger than the sum of its proper divisors (12517883).

81586585081 is a wasteful number, since it uses less digits than its factorization.

81586585081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12517882.

The product of its (nonzero) digits is 3072000, while the sum is 55.

The spelling of 81586585081 in words is "eighty-one billion, five hundred eighty-six million, five hundred eighty-five thousand, eighty-one".