21663223649549 has 2 divisors, whose sum is σ = 21663223649550. Its totient is φ = 21663223649548.

The previous prime is 21663223649539. The next prime is 21663223649563. The reversal of 21663223649549 is 94594632236612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21510719341225 + 152504308324 = 4637965^2 + 390518^2 .

It is a cyclic number.

It is not a de Polignac number, because 21663223649549 - 2⁴ = 21663223649533 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21663223649491 and 21663223649500.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21663223649519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10831611824774 + 10831611824775.

It is an arithmetic number, because the mean of its divisors is an integer number (10831611824775).

Almost surely, 2^{21663223649549} is an apocalyptic number.

It is an amenable number.

21663223649549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21663223649549 is an equidigital number, since it uses as much as digits as its factorization.

21663223649549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100776960, while the sum is 62.

The spelling of 21663223649549 in words is "twenty-one trillion, six hundred sixty-three billion, two hundred twenty-three million, six hundred forty-nine thousand, five hundred forty-nine".