81220620787 has 2 divisors, whose sum is σ = 81220620788. Its totient is φ = 81220620786.

The previous prime is 81220620763. The next prime is 81220620799. The reversal of 81220620787 is 78702602218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81220620787 - 2³¹ = 79073137139 is a prime.

It is not a weakly prime, because it can be changed into another prime (81220620487) 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 as a sum of consecutive naturals, namely, 40610310393 + 40610310394.

It is an arithmetic number, because the mean of its divisors is an integer number (40610310394).

Almost surely, 2^81220620787 is an apocalyptic number.

81220620787 is a deficient number, since it is larger than the sum of its proper divisors (1).

81220620787 is an equidigital number, since it uses as much as digits as its factorization.

81220620787 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 150528, while the sum is 43.

The spelling of 81220620787 in words is "eighty-one billion, two hundred twenty million, six hundred twenty thousand, seven hundred eighty-seven".