19899409991 has 2 divisors, whose sum is σ = 19899409992. Its totient is φ = 19899409990.

The previous prime is 19899409987. The next prime is 19899410009. The reversal of 19899409991 is 19990499891.

It is a weak prime.

It is an emirp because it is prime and its reverse (19990499891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19899409991 - 2² = 19899409987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19899409931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9949704995 + 9949704996.

It is an arithmetic number, because the mean of its divisors is an integer number (9949704996).

Almost surely, 2^19899409991 is an apocalyptic number.

19899409991 is a deficient number, since it is larger than the sum of its proper divisors (1).

19899409991 is an equidigital number, since it uses as much as digits as its factorization.

19899409991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17006112, while the sum is 68.

The spelling of 19899409991 in words is "nineteen billion, eight hundred ninety-nine million, four hundred nine thousand, nine hundred ninety-one".