19954858871809 has 2 divisors, whose sum is σ = 19954858871810. Its totient is φ = 19954858871808.

The previous prime is 19954858871749. The next prime is 19954858871821. The reversal of 19954858871809 is 90817885845991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19942163892225 + 12694979584 = 4465665^2 + 112672^2 .

It is an emirp because it is prime and its reverse (90817885845991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19954858871809 is a prime.

It is not a weakly prime, because it can be changed into another prime (19954858871209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9977429435904 + 9977429435905.

It is an arithmetic number, because the mean of its divisors is an integer number (9977429435905).

Almost surely, 2^{19954858871809} is an apocalyptic number.

It is an amenable number.

19954858871809 is a deficient number, since it is larger than the sum of its proper divisors (1).

19954858871809 is an equidigital number, since it uses as much as digits as its factorization.

19954858871809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2090188800, while the sum is 82.

The spelling of 19954858871809 in words is "nineteen trillion, nine hundred fifty-four billion, eight hundred fifty-eight million, eight hundred seventy-one thousand, eight hundred nine".