20731261776221 has 4 divisors (see below), whose sum is σ = 20734564516572. Its totient is φ = 20727959035872.

The previous prime is 20731261776163. The next prime is 20731261776361. The reversal of 20731261776221 is 12267716213702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10131425340100 + 10599836436121 = 3182990^2 + 3255739^2 .

It is a cyclic number.

It is not a de Polignac number, because 20731261776221 - 2¹⁸ = 20731261514077 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 (20731261773221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1651360760 + ... + 1651373313.

It is an arithmetic number, because the mean of its divisors is an integer number (5183641129143).

Almost surely, 2^{20731261776221} is an apocalyptic number.

It is an amenable number.

20731261776221 is a deficient number, since it is larger than the sum of its proper divisors (3302740351).

20731261776221 is an equidigital number, since it uses as much as digits as its factorization.

20731261776221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3302740350.

The product of its (nonzero) digits is 592704, while the sum is 47.

Adding to 20731261776221 its reverse (12267716213702), we get a palindrome (32998977989923).

The spelling of 20731261776221 in words is "twenty trillion, seven hundred thirty-one billion, two hundred sixty-one million, seven hundred seventy-six thousand, two hundred twenty-one".