21563823461 has 2 divisors, whose sum is σ = 21563823462. Its totient is φ = 21563823460.

The previous prime is 21563823419. The next prime is 21563823467. The reversal of 21563823461 is 16432836512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21110346436 + 453477025 = 145294^2 + 21295^2 .

It is a cyclic number.

It is not a de Polignac number, because 21563823461 - 2¹⁴ = 21563807077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21563823467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10781911730 + 10781911731.

It is an arithmetic number, because the mean of its divisors is an integer number (10781911731).

Almost surely, 2^21563823461 is an apocalyptic number.

It is an amenable number.

21563823461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21563823461 is an equidigital number, since it uses as much as digits as its factorization.

21563823461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 207360, while the sum is 41.

The spelling of 21563823461 in words is "twenty-one billion, five hundred sixty-three million, eight hundred twenty-three thousand, four hundred sixty-one".