81285120051 has 4 divisors (see below), whose sum is σ = 108380160072. Its totient is φ = 54190080032.

The previous prime is 81285120043. The next prime is 81285120053. The reversal of 81285120051 is 15002158218.

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 81285120051 - 2³ = 81285120043 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81285119994 and 81285120021.

It is not an unprimeable number, because it can be changed into a prime (81285120053) 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, 13547520006 + ... + 13547520011.

It is an arithmetic number, because the mean of its divisors is an integer number (27095040018).

Almost surely, 2^81285120051 is an apocalyptic number.

81285120051 is a deficient number, since it is larger than the sum of its proper divisors (27095040021).

81285120051 is a wasteful number, since it uses less digits than its factorization.

81285120051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27095040020.

The product of its (nonzero) digits is 6400, while the sum is 33.

Adding to 81285120051 its reverse (15002158218), we get a palindrome (96287278269).

The spelling of 81285120051 in words is "eighty-one billion, two hundred eighty-five million, one hundred twenty thousand, fifty-one".