81665120206 has 8 divisors (see below), whose sum is σ = 125346463704. Its totient is φ = 39882965640.

The previous prime is 81665120189. The next prime is 81665120233. The reversal of 81665120206 is 60202156618.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 474797125 + ... + 474797296.

It is an arithmetic number, because the mean of its divisors is an integer number (15668307963).

Almost surely, 2^81665120206 is an apocalyptic number.

81665120206 is a gapful number since it is divisible by the number (86) formed by its first and last digit.

81665120206 is a deficient number, since it is larger than the sum of its proper divisors (43681343498).

81665120206 is a wasteful number, since it uses less digits than its factorization.

81665120206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 949594466.

The product of its (nonzero) digits is 34560, while the sum is 37.

The spelling of 81665120206 in words is "eighty-one billion, six hundred sixty-five million, one hundred twenty thousand, two hundred six".