20812221791 has 2 divisors, whose sum is σ = 20812221792. Its totient is φ = 20812221790.

The previous prime is 20812221779. The next prime is 20812221811. The reversal of 20812221791 is 19712221802.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20812221791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20812223791) 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, 10406110895 + 10406110896.

It is an arithmetic number, because the mean of its divisors is an integer number (10406110896).

Almost surely, 2^20812221791 is an apocalyptic number.

20812221791 is a deficient number, since it is larger than the sum of its proper divisors (1).

20812221791 is an equidigital number, since it uses as much as digits as its factorization.

20812221791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 35.

The spelling of 20812221791 in words is "twenty billion, eight hundred twelve million, two hundred twenty-one thousand, seven hundred ninety-one".