81336979 has 2 divisors, whose sum is σ = 81336980. Its totient is φ = 81336978.

The previous prime is 81336977. The next prime is 81337001. The reversal of 81336979 is 97963318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81336979 - 2¹ = 81336977 is a prime.

Together with 81336977, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81336977) 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, 40668489 + 40668490.

It is an arithmetic number, because the mean of its divisors is an integer number (40668490).

Almost surely, 2^81336979 is an apocalyptic number.

81336979 is a deficient number, since it is larger than the sum of its proper divisors (1).

81336979 is an equidigital number, since it uses as much as digits as its factorization.

81336979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 46.

The square root of 81336979 is about 9018.7016249569. The cubic root of 81336979 is about 433.2740506015.

The spelling of 81336979 in words is "eighty-one million, three hundred thirty-six thousand, nine hundred seventy-nine".