20621132563261 has 4 divisors (see below), whose sum is σ = 20626710368572. Its totient is φ = 20615554757952.

The previous prime is 20621132563247. The next prime is 20621132563267. The reversal of 20621132563261 is 16236523112602.

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 11841650968900 + 8779481594361 = 3441170^2 + 2963019^2 .

It is a cyclic number.

It is not a de Polignac number, because 20621132563261 - 2⁹ = 20621132562749 is a prime.

It is a super-3 number, since 3×20621132563261³ (a number of 41 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20621132563267) 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 in 3 ways as a sum of consecutive naturals, for example, 2788897110 + ... + 2788904503.

It is an arithmetic number, because the mean of its divisors is an integer number (5156677592143).

Almost surely, 2^{20621132563261} is an apocalyptic number.

It is an amenable number.

20621132563261 is a deficient number, since it is larger than the sum of its proper divisors (5577805311).

20621132563261 is an equidigital number, since it uses as much as digits as its factorization.

20621132563261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5577805310.

The product of its (nonzero) digits is 155520, while the sum is 40.

Adding to 20621132563261 its reverse (16236523112602), we get a palindrome (36857655675863).

The spelling of 20621132563261 in words is "twenty trillion, six hundred twenty-one billion, one hundred thirty-two million, five hundred sixty-three thousand, two hundred sixty-one".