81171827133 has 4 divisors (see below), whose sum is σ = 108229102848. Its totient is φ = 54114551420.

The previous prime is 81171827131. The next prime is 81171827153. The reversal of 81171827133 is 33172817118.

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 81171827133 - 2¹ = 81171827131 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81171827131) 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, 13528637853 + ... + 13528637858.

It is an arithmetic number, because the mean of its divisors is an integer number (27057275712).

Almost surely, 2^81171827133 is an apocalyptic number.

It is an amenable number.

81171827133 is a deficient number, since it is larger than the sum of its proper divisors (27057275715).

81171827133 is a wasteful number, since it uses less digits than its factorization.

81171827133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27057275714.

The product of its digits is 56448, while the sum is 42.

The spelling of 81171827133 in words is "eighty-one billion, one hundred seventy-one million, eight hundred twenty-seven thousand, one hundred thirty-three".