81116779 has 4 divisors (see below), whose sum is σ = 81565120. Its totient is φ = 80668440.

The previous prime is 81116773. The next prime is 81116803. The reversal of 81116779 is 97761118.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81116779 - 2⁹ = 81116267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81116773) 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 3 ways as a sum of consecutive naturals, for example, 223899 + ... + 224260.

It is an arithmetic number, because the mean of its divisors is an integer number (20391280).

Almost surely, 2^81116779 is an apocalyptic number.

81116779 is a deficient number, since it is larger than the sum of its proper divisors (448341).

81116779 is a wasteful number, since it uses less digits than its factorization.

81116779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448340.

The product of its digits is 21168, while the sum is 40.

The square root of 81116779 is about 9006.4853855430. The cubic root of 81116779 is about 432.8827026814.

The spelling of 81116779 in words is "eighty-one million, one hundred sixteen thousand, seven hundred seventy-nine".