81811695456 has 72 divisors (see below), whose sum is σ = 233617568184. Its totient is φ = 27157386240.

The previous prime is 81811695439. The next prime is 81811695503. The reversal of 81811695456 is 65459611818.

81811695456 is a `hidden beast` number, since 8 + 1 + 81 + 16 + 9 + 545 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

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 11 ways as a sum of consecutive naturals, for example, 519946 + ... + 658761.

It is an arithmetic number, because the mean of its divisors is an integer number (3244688447).

Almost surely, 2^81811695456 is an apocalyptic number.

It is an amenable number.

81811695456 is an abundant number, since it is smaller than the sum of its proper divisors (151805872728).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81811695456 is a wasteful number, since it uses less digits than its factorization.

81811695456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1178964 (or 1178953 counting only the distinct ones).

The product of its digits is 2073600, while the sum is 54.

The spelling of 81811695456 in words is "eighty-one billion, eight hundred eleven million, six hundred ninety-five thousand, four hundred fifty-six".