81757792679 has 4 divisors (see below), whose sum is σ = 82124419776. Its totient is φ = 81391165584.

The previous prime is 81757792667. The next prime is 81757792687. The reversal of 81757792679 is 97629775718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97629775718 = 2 ⋅48814887859.

It is a cyclic number.

It is not a de Polignac number, because 81757792679 - 2¹² = 81757788583 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81757792639) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 183313214 + ... + 183313659.

It is an arithmetic number, because the mean of its divisors is an integer number (20531104944).

Almost surely, 2^81757792679 is an apocalyptic number.

81757792679 is a deficient number, since it is larger than the sum of its proper divisors (366627097).

81757792679 is a wasteful number, since it uses less digits than its factorization.

81757792679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 366627096.

The product of its digits is 93350880, while the sum is 68.

The spelling of 81757792679 in words is "eighty-one billion, seven hundred fifty-seven million, seven hundred ninety-two thousand, six hundred seventy-nine".