20898911785 has 4 divisors (see below), whose sum is σ = 25078694148. Its totient is φ = 16719129424.

The previous prime is 20898911779. The next prime is 20898911807. The reversal of 20898911785 is 58711989802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58711989802 = 2 ⋅29355994901.

It can be written as a sum of positive squares in 2 ways, for example, as 7075501456 + 13823410329 = 84116^2 + 117573^2 .

It is a cyclic number.

It is not a de Polignac number, because 20898911785 - 2³ = 20898911777 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 2089891174 + ... + 2089891183.

It is an arithmetic number, because the mean of its divisors is an integer number (6269673537).

Almost surely, 2^20898911785 is an apocalyptic number.

It is an amenable number.

20898911785 is a deficient number, since it is larger than the sum of its proper divisors (4179782363).

20898911785 is an equidigital number, since it uses as much as digits as its factorization.

20898911785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4179782362.

The product of its (nonzero) digits is 2903040, while the sum is 58.

The spelling of 20898911785 in words is "twenty billion, eight hundred ninety-eight million, nine hundred eleven thousand, seven hundred eighty-five".