81198711 has 24 divisors (see below), whose sum is σ = 129207936. Its totient is φ = 48727440.

The previous prime is 81198709. The next prime is 81198721. The reversal of 81198711 is 11789118.

It is a happy number.

It is not a de Polignac number, because 81198711 - 2¹ = 81198709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81198701) 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 23 ways as a sum of consecutive naturals, for example, 6216 + ... + 14178.

It is an arithmetic number, because the mean of its divisors is an integer number (5383664).

Almost surely, 2^81198711 is an apocalyptic number.

81198711 is a deficient number, since it is larger than the sum of its proper divisors (48009225).

81198711 is a wasteful number, since it uses less digits than its factorization.

81198711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8083 (or 8080 counting only the distinct ones).

The product of its digits is 4032, while the sum is 36.

The square root of 81198711 is about 9011.0327377055. The cubic root of 81198711 is about 433.0283980258.

The spelling of 81198711 in words is "eighty-one million, one hundred ninety-eight thousand, seven hundred eleven".