81510859407205 has 4 divisors (see below), whose sum is σ = 97813031288652. Its totient is φ = 65208687525760.

The previous prime is 81510859407193. The next prime is 81510859407293. The reversal of 81510859407205 is 50270495801518.

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 23171341850244 + 58339517556961 = 4813662^2 + 7638031^2 .

It is not a de Polignac number, because 81510859407205 - 2²¹ = 81510857310053 is a prime.

It is a super-2 number, since 2×81510859407205² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8151085940716 + ... + 8151085940725.

It is an arithmetic number, because the mean of its divisors is an integer number (24453257822163).

Almost surely, 2^{81510859407205} is an apocalyptic number.

It is an amenable number.

81510859407205 is a deficient number, since it is larger than the sum of its proper divisors (16302171881447).

81510859407205 is a wasteful number, since it uses less digits than its factorization.

81510859407205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16302171881446.

The product of its (nonzero) digits is 4032000, while the sum is 55.

The spelling of 81510859407205 in words is "eighty-one trillion, five hundred ten billion, eight hundred fifty-nine million, four hundred seven thousand, two hundred five".