81708221911 has 2 divisors, whose sum is σ = 81708221912. Its totient is φ = 81708221910.

The previous prime is 81708221909. The next prime is 81708221939. The reversal of 81708221911 is 11912280718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81708221911 - 2¹ = 81708221909 is a prime.

Together with 81708221909, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81708221941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40854110955 + 40854110956.

It is an arithmetic number, because the mean of its divisors is an integer number (40854110956).

Almost surely, 2^81708221911 is an apocalyptic number.

81708221911 is a deficient number, since it is larger than the sum of its proper divisors (1).

81708221911 is an equidigital number, since it uses as much as digits as its factorization.

81708221911 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 40.

The spelling of 81708221911 in words is "eighty-one billion, seven hundred eight million, two hundred twenty-one thousand, nine hundred eleven".