21221033012261 has 2 divisors, whose sum is σ = 21221033012262. Its totient is φ = 21221033012260.

The previous prime is 21221033012243. The next prime is 21221033012269. The reversal of 21221033012261 is 16221033012212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15055222571236 + 6165810441025 = 3880106^2 + 2483105^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221033012261 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21221033012261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221033012269) 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 as a sum of consecutive naturals, namely, 10610516506130 + 10610516506131.

It is an arithmetic number, because the mean of its divisors is an integer number (10610516506131).

Almost surely, 2^{21221033012261} is an apocalyptic number.

It is an amenable number.

21221033012261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221033012261 is an equidigital number, since it uses as much as digits as its factorization.

21221033012261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 26.

Adding to 21221033012261 its reverse (16221033012212), we get a palindrome (37442066024473).

The spelling of 21221033012261 in words is "twenty-one trillion, two hundred twenty-one billion, thirty-three million, twelve thousand, two hundred sixty-one".