81811198 has 16 divisors (see below), whose sum is σ = 143510400. Its totient is φ = 34246296.

The previous prime is 81811159. The next prime is 81811199. The reversal of 81811198 is 89111818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81811199) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67348 + ... + 68551.

It is an arithmetic number, because the mean of its divisors is an integer number (8969400).

Almost surely, 2^81811198 is an apocalyptic number.

81811198 is a deficient number, since it is larger than the sum of its proper divisors (61699202).

81811198 is a wasteful number, since it uses less digits than its factorization.

81811198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135951.

The product of its digits is 4608, while the sum is 37.

The square root of 81811198 is about 9044.9542840194. The cubic root of 81811198 is about 434.1144586869.

The spelling of 81811198 in words is "eighty-one million, eight hundred eleven thousand, one hundred ninety-eight".