21550427243861 has 2 divisors, whose sum is σ = 21550427243862. Its totient is φ = 21550427243860.

The previous prime is 21550427243797. The next prime is 21550427243879. The reversal of 21550427243861 is 16834272405512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19790095343236 + 1760331900625 = 4448606^2 + 1326775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21550427243861 - 2⁶ = 21550427243797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21550427240861) 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 as a sum of consecutive naturals, namely, 10775213621930 + 10775213621931.

It is an arithmetic number, because the mean of its divisors is an integer number (10775213621931).

Almost surely, 2^{21550427243861} is an apocalyptic number.

It is an amenable number.

21550427243861 is a deficient number, since it is larger than the sum of its proper divisors (1).

21550427243861 is an equidigital number, since it uses as much as digits as its factorization.

21550427243861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3225600, while the sum is 50.

The spelling of 21550427243861 in words is "twenty-one trillion, five hundred fifty billion, four hundred twenty-seven million, two hundred forty-three thousand, eight hundred sixty-one".