81220620799 has 2 divisors, whose sum is σ = 81220620800. Its totient is φ = 81220620798.

The previous prime is 81220620787. The next prime is 81220620829. The reversal of 81220620799 is 99702602218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81220620799 - 2¹⁹ = 81220096511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81220620499) by changing a digit.

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 as a sum of consecutive naturals, namely, 40610310399 + 40610310400.

It is an arithmetic number, because the mean of its divisors is an integer number (40610310400).

Almost surely, 2^81220620799 is an apocalyptic number.

81220620799 is a deficient number, since it is larger than the sum of its proper divisors (1).

81220620799 is an equidigital number, since it uses as much as digits as its factorization.

81220620799 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 217728, while the sum is 46.

The spelling of 81220620799 in words is "eighty-one billion, two hundred twenty million, six hundred twenty thousand, seven hundred ninety-nine".