20973921791 has 2 divisors, whose sum is σ = 20973921792. Its totient is φ = 20973921790.

The previous prime is 20973921757. The next prime is 20973921797. The reversal of 20973921791 is 19712937902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20973921791 - 2¹⁰ = 20973920767 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20973921797) 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, 10486960895 + 10486960896.

It is an arithmetic number, because the mean of its divisors is an integer number (10486960896).

Almost surely, 2^20973921791 is an apocalyptic number.

20973921791 is a deficient number, since it is larger than the sum of its proper divisors (1).

20973921791 is an equidigital number, since it uses as much as digits as its factorization.

20973921791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 428652, while the sum is 50.

The spelling of 20973921791 in words is "twenty billion, nine hundred seventy-three million, nine hundred twenty-one thousand, seven hundred ninety-one".