81186909099 has 16 divisors (see below), whose sum is σ = 113375635200. Its totient is φ = 51578891936.

The previous prime is 81186909077. The next prime is 81186909107. The reversal of 81186909099 is 99090968118.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81186909099 - 2⁸ = 81186908843 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81186909059) 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, 2168469 + ... + 2205590.

It is an arithmetic number, because the mean of its divisors is an integer number (7085977200).

Almost surely, 2^81186909099 is an apocalyptic number.

81186909099 is a deficient number, since it is larger than the sum of its proper divisors (32188726101).

81186909099 is a wasteful number, since it uses less digits than its factorization.

81186909099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4374354.

The product of its (nonzero) digits is 2519424, while the sum is 60.

The spelling of 81186909099 in words is "eighty-one billion, one hundred eighty-six million, nine hundred nine thousand, ninety-nine".