19998449544961 has 2 divisors, whose sum is σ = 19998449544962. Its totient is φ = 19998449544960.

The previous prime is 19998449544919. The next prime is 19998449544979. The reversal of 19998449544961 is 16944594489991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19959583788225 + 38865756736 = 4467615^2 + 197144^2 .

It is a cyclic number.

It is not a de Polignac number, because 19998449544961 - 2¹⁹ = 19998449020673 is a prime.

It is not a weakly prime, because it can be changed into another prime (19998449544901) 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, 9999224772480 + 9999224772481.

It is an arithmetic number, because the mean of its divisors is an integer number (9999224772481).

Almost surely, 2^{19998449544961} is an apocalyptic number.

It is an amenable number.

19998449544961 is a deficient number, since it is larger than the sum of its proper divisors (1).

19998449544961 is an equidigital number, since it uses as much as digits as its factorization.

19998449544961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3627970560, while the sum is 82.

The spelling of 19998449544961 in words is "nineteen trillion, nine hundred ninety-eight billion, four hundred forty-nine million, five hundred forty-four thousand, nine hundred sixty-one".