20910805897 has 2 divisors, whose sum is σ = 20910805898. Its totient is φ = 20910805896.

The previous prime is 20910805849. The next prime is 20910805913. The reversal of 20910805897 is 79850801902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18137624976 + 2773180921 = 134676^2 + 52661^2 .

It is a cyclic number.

It is not a de Polignac number, because 20910805897 - 2²⁷ = 20776588169 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20910805897.

It is not a weakly prime, because it can be changed into another prime (20910803897) 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, 10455402948 + 10455402949.

It is an arithmetic number, because the mean of its divisors is an integer number (10455402949).

Almost surely, 2^20910805897 is an apocalyptic number.

It is an amenable number.

20910805897 is a deficient number, since it is larger than the sum of its proper divisors (1).

20910805897 is an equidigital number, since it uses as much as digits as its factorization.

20910805897 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 362880, while the sum is 49.

The spelling of 20910805897 in words is "twenty billion, nine hundred ten million, eight hundred five thousand, eight hundred ninety-seven".