81171827053 has 4 divisors (see below), whose sum is σ = 81172411900. Its totient is φ = 81171242208.

The previous prime is 81171827039. The next prime is 81171827063. The reversal of 81171827053 is 35072817118.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 35072817118 = 2 ⋅17536408559.

It can be written as a sum of positive squares in 2 ways, for example, as 23032008169 + 58139818884 = 151763^2 + 241122^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81171827053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81171827063) 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, 47401 + ... + 405697.

It is an arithmetic number, because the mean of its divisors is an integer number (20293102975).

Almost surely, 2^81171827053 is an apocalyptic number.

It is an amenable number.

81171827053 is a deficient number, since it is larger than the sum of its proper divisors (584847).

81171827053 is a wasteful number, since it uses less digits than its factorization.

81171827053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 584846.

The product of its (nonzero) digits is 94080, while the sum is 43.

The spelling of 81171827053 in words is "eighty-one billion, one hundred seventy-one million, eight hundred twenty-seven thousand, fifty-three".