81855521353 has 4 divisors (see below), whose sum is σ = 85414457088. Its totient is φ = 78296585620.

The previous prime is 81855521311. The next prime is 81855521369. The reversal of 81855521353 is 35312555818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81855521353 - 2²⁵ = 81821966921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81855521753) 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, 1779467833 + ... + 1779467878.

It is an arithmetic number, because the mean of its divisors is an integer number (21353614272).

Almost surely, 2^81855521353 is an apocalyptic number.

It is an amenable number.

81855521353 is a deficient number, since it is larger than the sum of its proper divisors (3558935735).

81855521353 is a wasteful number, since it uses less digits than its factorization.

81855521353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3558935734.

The product of its digits is 720000, while the sum is 46.

The spelling of 81855521353 in words is "eighty-one billion, eight hundred fifty-five million, five hundred twenty-one thousand, three hundred fifty-three".