21420388457161 has 2 divisors, whose sum is σ = 21420388457162. Its totient is φ = 21420388457160.

The previous prime is 21420388457137. The next prime is 21420388457179. The reversal of 21420388457161 is 16175488302412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12230274946761 + 9190113510400 = 3497181^2 + 3031520^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420388457161 - 2³⁷ = 21282949503689 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21420388457099 and 21420388457108.

It is not a weakly prime, because it can be changed into another prime (21420382457161) 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, 10710194228580 + 10710194228581.

It is an arithmetic number, because the mean of its divisors is an integer number (10710194228581).

Almost surely, 2^{21420388457161} is an apocalyptic number.

It is an amenable number.

21420388457161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420388457161 is an equidigital number, since it uses as much as digits as its factorization.

21420388457161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2580480, while the sum is 52.

The spelling of 21420388457161 in words is "twenty-one trillion, four hundred twenty billion, three hundred eighty-eight million, four hundred fifty-seven thousand, one hundred sixty-one".