81911108 has 6 divisors (see below), whose sum is σ = 143344446. Its totient is φ = 40955552.

The previous prime is 81911107. The next prime is 81911197. The reversal of 81911108 is 80111918.

It can be written as a sum of positive squares in only one way, i.e., 81577024 + 334084 = 9032^2 + 578^2 .

It is a super-2 number, since 2×81911108² = 13418859227575328, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81911107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10238885 + ... + 10238892.

It is an arithmetic number, because the mean of its divisors is an integer number (23890741).

Almost surely, 2^81911108 is an apocalyptic number.

It is an amenable number.

81911108 is a deficient number, since it is larger than the sum of its proper divisors (61433338).

81911108 is a wasteful number, since it uses less digits than its factorization.

81911108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20477781 (or 20477779 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 29.

The square root of 81911108 is about 9050.4755676152. The cubic root of 81911108 is about 434.2911041534.

The spelling of 81911108 in words is "eighty-one million, nine hundred eleven thousand, one hundred eight".