81911806 has 8 divisors (see below), whose sum is σ = 122908104. Its totient is φ = 40942440.

The previous prime is 81911771. The next prime is 81911813. The reversal of 81911806 is 60811918.

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 pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4876 + ... + 13696.

It is an arithmetic number, because the mean of its divisors is an integer number (15363513).

Almost surely, 2^81911806 is an apocalyptic number.

81911806 is a deficient number, since it is larger than the sum of its proper divisors (40996298).

81911806 is a wasteful number, since it uses less digits than its factorization.

81911806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13466.

The product of its (nonzero) digits is 3456, while the sum is 34.

The square root of 81911806 is about 9050.5141290426. The cubic root of 81911806 is about 434.2923377440.

The spelling of 81911806 in words is "eighty-one million, nine hundred eleven thousand, eight hundred six".