81835980605 has 4 divisors (see below), whose sum is σ = 98203176732. Its totient is φ = 65468784480.

The previous prime is 81835980601. The next prime is 81835980613. The reversal of 81835980605 is 50608953818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50608953818 = 2 ⋅25304476909.

It can be written as a sum of positive squares in 2 ways, for example, as 39671875684 + 42164104921 = 199178^2 + 205339^2 .

It is not a de Polignac number, because 81835980605 - 2² = 81835980601 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 (81835980601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8183598056 + ... + 8183598065.

It is an arithmetic number, because the mean of its divisors is an integer number (24550794183).

Almost surely, 2^81835980605 is an apocalyptic number.

It is an amenable number.

81835980605 is a deficient number, since it is larger than the sum of its proper divisors (16367196127).

81835980605 is a wasteful number, since it uses less digits than its factorization.

81835980605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16367196126.

The product of its (nonzero) digits is 2073600, while the sum is 53.

The spelling of 81835980605 in words is "eighty-one billion, eight hundred thirty-five million, nine hundred eighty thousand, six hundred five".