21805474360349 has 2 divisors, whose sum is σ = 21805474360350. Its totient is φ = 21805474360348.

The previous prime is 21805474360309. The next prime is 21805474360363. The reversal of 21805474360349 is 94306347450812.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21643830157849 + 161644202500 = 4652293^2 + 402050^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21805474360349 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21805474360294 and 21805474360303.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21805474360309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10902737180174 + 10902737180175.

It is an arithmetic number, because the mean of its divisors is an integer number (10902737180175).

It is a 1-persistent number, because it is pandigital, but 2⋅21805474360349 = 43610948720698 is not.

Almost surely, 2^{21805474360349} is an apocalyptic number.

It is an amenable number.

21805474360349 is a deficient number, since it is larger than the sum of its proper divisors (1).

21805474360349 is an equidigital number, since it uses as much as digits as its factorization.

21805474360349 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17418240, while the sum is 56.

The spelling of 21805474360349 in words is "twenty-one trillion, eight hundred five billion, four hundred seventy-four million, three hundred sixty thousand, three hundred forty-nine".