81931161288705 has 32 divisors (see below), whose sum is σ = 131180095952640. Its totient is φ = 43666542581760.

The previous prime is 81931161288643. The next prime is 81931161288709. The reversal of 81931161288705 is 50788216113918.

It is not a de Polignac number, because 81931161288705 - 2¹¹ = 81931161286657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81931161288709) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 635213461 + ... + 635342429.

It is an arithmetic number, because the mean of its divisors is an integer number (4099377998520).

Almost surely, 2^{81931161288705} is an apocalyptic number.

It is an amenable number.

81931161288705 is a deficient number, since it is larger than the sum of its proper divisors (49248934663935).

81931161288705 is a wasteful number, since it uses less digits than its factorization.

81931161288705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157801.

The product of its (nonzero) digits is 5806080, while the sum is 60.

The spelling of 81931161288705 in words is "eighty-one trillion, nine hundred thirty-one billion, one hundred sixty-one million, two hundred eighty-eight thousand, seven hundred five".