81798772188 has 48 divisors (see below), whose sum is σ = 227613980160. Its totient is φ = 22354943424.

The previous prime is 81798772171. The next prime is 81798772189. The reversal of 81798772188 is 88127789718.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81798772189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21167523 + ... + 21171386.

It is an arithmetic number, because the mean of its divisors is an integer number (4741957920).

Almost surely, 2^81798772188 is an apocalyptic number.

It is an amenable number.

81798772188 is an abundant number, since it is smaller than the sum of its proper divisors (145815207972).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81798772188 is a wasteful number, since it uses less digits than its factorization.

81798772188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42338946 (or 42338944 counting only the distinct ones).

The product of its digits is 25288704, while the sum is 66.

The spelling of 81798772188 in words is "eighty-one billion, seven hundred ninety-eight million, seven hundred seventy-two thousand, one hundred eighty-eight".