81961713854775 has 72 divisors (see below), whose sum is σ = 156481188692400. Its totient is φ = 40865447992320.

The previous prime is 81961713854767. The next prime is 81961713854791. The reversal of 81961713854775 is 57745831716918.

81961713854775 is a `hidden beast` number, since 8 + 1 + 9 + 6 + 1 + 7 + 1 + 3 + 8 + 547 + 75 = 666.

It is not a de Polignac number, because 81961713854775 - 2³ = 81961713854767 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 71335777 + ... + 72475626.

It is an arithmetic number, because the mean of its divisors is an integer number (2173349842950).

Almost surely, 2^{81961713854775} is an apocalyptic number.

81961713854775 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81961713854775 is a deficient number, since it is larger than the sum of its proper divisors (74519474837625).

81961713854775 is a wasteful number, since it uses less digits than its factorization.

81961713854775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143811585 (or 143811577 counting only the distinct ones).

The product of its digits is 355622400, while the sum is 72.

The spelling of 81961713854775 in words is "eighty-one trillion, nine hundred sixty-one billion, seven hundred thirteen million, eight hundred fifty-four thousand, seven hundred seventy-five".