81791896465 has 4 divisors (see below), whose sum is σ = 98150275764. Its totient is φ = 65433517168.

The previous prime is 81791896441. The next prime is 81791896469. The reversal of 81791896465 is 56469819718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15225832449 + 66566064016 = 123393^2 + 258004^2 .

It is a cyclic number.

It is not a de Polignac number, because 81791896465 - 2¹³ = 81791888273 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81791896397 and 81791896406.

It is not an unprimeable number, because it can be changed into a prime (81791896469) 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, 8179189642 + ... + 8179189651.

It is an arithmetic number, because the mean of its divisors is an integer number (24537568941).

Almost surely, 2^81791896465 is an apocalyptic number.

It is an amenable number.

81791896465 is a deficient number, since it is larger than the sum of its proper divisors (16358379299).

81791896465 is a wasteful number, since it uses less digits than its factorization.

81791896465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16358379298.

The product of its digits is 26127360, while the sum is 64.

The spelling of 81791896465 in words is "eighty-one billion, seven hundred ninety-one million, eight hundred ninety-six thousand, four hundred sixty-five".