21755421445013 has 2 divisors, whose sum is σ = 21755421445014. Its totient is φ = 21755421445012.

The previous prime is 21755421445007. The next prime is 21755421445157. The reversal of 21755421445013 is 31054412455712.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20654688936049 + 1100732508964 = 4544743^2 + 1049158^2 .

It is a cyclic number.

It is not a de Polignac number, because 21755421445013 - 2³⁰ = 21754347703189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21755426445013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10877710722506 + 10877710722507.

It is an arithmetic number, because the mean of its divisors is an integer number (10877710722507).

Almost surely, 2^{21755421445013} is an apocalyptic number.

It is an amenable number.

21755421445013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21755421445013 is an equidigital number, since it uses as much as digits as its factorization.

21755421445013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672000, while the sum is 44.

The spelling of 21755421445013 in words is "twenty-one trillion, seven hundred fifty-five billion, four hundred twenty-one million, four hundred forty-five thousand, thirteen".