19891812089 has 2 divisors, whose sum is σ = 19891812090. Its totient is φ = 19891812088.

The previous prime is 19891812053. The next prime is 19891812103. The reversal of 19891812089 is 98021819891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17763558400 + 2128253689 = 133280^2 + 46133^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19891812089 is a prime.

It is not a weakly prime, because it can be changed into another prime (19891812389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9945906044 + 9945906045.

It is an arithmetic number, because the mean of its divisors is an integer number (9945906045).

Almost surely, 2^19891812089 is an apocalyptic number.

It is an amenable number.

19891812089 is a deficient number, since it is larger than the sum of its proper divisors (1).

19891812089 is an equidigital number, since it uses as much as digits as its factorization.

19891812089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 746496, while the sum is 56.

The spelling of 19891812089 in words is "nineteen billion, eight hundred ninety-one million, eight hundred twelve thousand, eighty-nine".