81198309 has 8 divisors (see below), whose sum is σ = 108308512. Its totient is φ = 54110160.

The previous prime is 81198301. The next prime is 81198323. The reversal of 81198309 is 90389118.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81198309 - 2³ = 81198301 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 (81198301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7407 + ... + 14739.

It is an arithmetic number, because the mean of its divisors is an integer number (13538564).

Almost surely, 2^81198309 is an apocalyptic number.

It is an amenable number.

81198309 is a deficient number, since it is larger than the sum of its proper divisors (27110203).

81198309 is a wasteful number, since it uses less digits than its factorization.

81198309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11027.

The product of its (nonzero) digits is 15552, while the sum is 39.

The square root of 81198309 is about 9011.0104316886. The cubic root of 81198309 is about 433.0276834098.

The spelling of 81198309 in words is "eighty-one million, one hundred ninety-eight thousand, three hundred nine".