20811658521221 has 8 divisors (see below), whose sum is σ = 21046011643800. Its totient is φ = 20577316826880.

The previous prime is 20811658521097. The next prime is 20811658521223. The reversal of 20811658521221 is 12212585611802.

It can be written as a sum of positive squares in 4 ways, for example, as 450897477121 + 20360761044100 = 671489^2 + 4512290^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20811658521221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20811658521223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 832265 + ... + 6505073.

It is an arithmetic number, because the mean of its divisors is an integer number (2630751455475).

Almost surely, 2^{20811658521221} is an apocalyptic number.

It is an amenable number.

20811658521221 is a deficient number, since it is larger than the sum of its proper divisors (234353122579).

20811658521221 is an equidigital number, since it uses as much as digits as its factorization.

20811658521221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5714119.

The product of its (nonzero) digits is 153600, while the sum is 44.

The spelling of 20811658521221 in words is "twenty trillion, eight hundred eleven billion, six hundred fifty-eight million, five hundred twenty-one thousand, two hundred twenty-one".