81211711712 has 12 divisors (see below), whose sum is σ = 159885557496. Its totient is φ = 40605855840.

The previous prime is 81211711709. The next prime is 81211711733. The reversal of 81211711712 is 21711711218.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (32), and also a Moran number because the ratio is a prime number: 2537865991 = 81211711712 / (8 + 1 + 2 + 1 + 1 + 7 + 1 + 1 + 7 + 1 + 2).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1268932964 + ... + 1268933027.

It is an arithmetic number, because the mean of its divisors is an integer number (13323796458).

Almost surely, 2^81211711712 is an apocalyptic number.

It is an amenable number.

81211711712 is a deficient number, since it is larger than the sum of its proper divisors (78673845784).

81211711712 is a wasteful number, since it uses less digits than its factorization.

81211711712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2537866001 (or 2537865993 counting only the distinct ones).

The product of its digits is 1568, while the sum is 32.

The spelling of 81211711712 in words is "eighty-one billion, two hundred eleven million, seven hundred eleven thousand, seven hundred twelve".