81585406051 has 4 divisors (see below), whose sum is σ = 81637941672. Its totient is φ = 81532870432.

The previous prime is 81585406043. The next prime is 81585406103. The reversal of 81585406051 is 15060458518.

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

It is a cyclic number.

It is not a de Polignac number, because 81585406051 - 2³ = 81585406043 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81585405989 and 81585406007.

It is not an unprimeable number, because it can be changed into a prime (81585406451) 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, 26265481 + ... + 26268586.

It is an arithmetic number, because the mean of its divisors is an integer number (20409485418).

Almost surely, 2^81585406051 is an apocalyptic number.

81585406051 is a deficient number, since it is larger than the sum of its proper divisors (52535621).

81585406051 is a wasteful number, since it uses less digits than its factorization.

81585406051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52535620.

The product of its (nonzero) digits is 192000, while the sum is 43.

The spelling of 81585406051 in words is "eighty-one billion, five hundred eighty-five million, four hundred six thousand, fifty-one".