81261835199 has 16 divisors (see below), whose sum is σ = 84073675776. Its totient is φ = 78501852000.

The previous prime is 81261835183. The next prime is 81261835211. The reversal of 81261835199 is 99153816218.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81261835199 - 2⁴ = 81261835183 is a prime.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81261835199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81261832199) 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 15 ways as a sum of consecutive naturals, for example, 1077764 + ... + 1150694.

It is an arithmetic number, because the mean of its divisors is an integer number (5254604736).

Almost surely, 2^81261835199 is an apocalyptic number.

81261835199 is a deficient number, since it is larger than the sum of its proper divisors (2811840577).

81261835199 is a wasteful number, since it uses less digits than its factorization.

81261835199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73286.

The product of its digits is 933120, while the sum is 53.

The spelling of 81261835199 in words is "eighty-one billion, two hundred sixty-one million, eight hundred thirty-five thousand, one hundred ninety-nine".