81977804899 has 2 divisors, whose sum is σ = 81977804900. Its totient is φ = 81977804898.

The previous prime is 81977804893. The next prime is 81977804903. The reversal of 81977804899 is 99840877918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81977804899 - 2⁹ = 81977804387 is a prime.

It is not a weakly prime, because it can be changed into another prime (81977804893) 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, 40988902449 + 40988902450.

It is an arithmetic number, because the mean of its divisors is an integer number (40988902450).

Almost surely, 2^81977804899 is an apocalyptic number.

81977804899 is a deficient number, since it is larger than the sum of its proper divisors (1).

81977804899 is an equidigital number, since it uses as much as digits as its factorization.

81977804899 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 73156608, while the sum is 70.

The spelling of 81977804899 in words is "eighty-one billion, nine hundred seventy-seven million, eight hundred four thousand, eight hundred ninety-nine".