81211711725 has 84 divisors (see below), whose sum is σ = 151894507296. Its totient is φ = 43051940640.

The previous prime is 81211711709. The next prime is 81211711733. The reversal of 81211711725 is 52711711218.

It is not a de Polignac number, because 81211711725 - 2⁴ = 81211711709 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81211711725.

It is a congruent number.

It is an unprimeable number.

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 83 ways as a sum of consecutive naturals, for example, 3030234 + ... + 3056916.

It is an arithmetic number, because the mean of its divisors is an integer number (1808267944).

Almost surely, 2^81211711725 is an apocalyptic number.

It is an amenable number.

81211711725 is a deficient number, since it is larger than the sum of its proper divisors (70682795571).

81211711725 is a wasteful number, since it uses less digits than its factorization.

81211711725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26878 (or 26858 counting only the distinct ones).

The product of its digits is 7840, while the sum is 36.

The spelling of 81211711725 in words is "eighty-one billion, two hundred eleven million, seven hundred eleven thousand, seven hundred twenty-five".