19891812389 has 2 divisors, whose sum is σ = 19891812390. Its totient is φ = 19891812388.

The previous prime is 19891812379. The next prime is 19891812403. The reversal of 19891812389 is 98321819891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12071416900 + 7820395489 = 109870^2 + 88433^2 .

It is a cyclic number.

It is not a de Polignac number, because 19891812389 - 2³² = 15596845093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19891812349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9945906194 + 9945906195.

It is an arithmetic number, because the mean of its divisors is an integer number (9945906195).

Almost surely, 2^19891812389 is an apocalyptic number.

It is an amenable number.

19891812389 is a deficient number, since it is larger than the sum of its proper divisors (1).

19891812389 is an equidigital number, since it uses as much as digits as its factorization.

19891812389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2239488, while the sum is 59.

The spelling of 19891812389 in words is "nineteen billion, eight hundred ninety-one million, eight hundred twelve thousand, three hundred eighty-nine".