20806821071 has 2 divisors, whose sum is σ = 20806821072. Its totient is φ = 20806821070.

The previous prime is 20806821031. The next prime is 20806821073. The reversal of 20806821071 is 17012860802.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20806821071 is a prime.

Together with 20806821073, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20806821073) 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, 10403410535 + 10403410536.

It is an arithmetic number, because the mean of its divisors is an integer number (10403410536).

Almost surely, 2^20806821071 is an apocalyptic number.

20806821071 is a deficient number, since it is larger than the sum of its proper divisors (1).

20806821071 is an equidigital number, since it uses as much as digits as its factorization.

20806821071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 35.

The spelling of 20806821071 in words is "twenty billion, eight hundred six million, eight hundred twenty-one thousand, seventy-one".